idk if you’ve been asked this before sorry but I’m still quite confused as to how many Hogwarts students there are per house per year. It seems in Harry’s year there are only 5 Gryffindor boys, including him, and they all share a dorm. So is this the norm for there to be so few students per house per year that there’s always a small enough number in the same year for them all to share a dorm? Perhaps this is only a Gryffindor thing and one or more of the other houses have different dorm distributions?
So, I go back and forth on this question a lot and you can find different posts on this blog for both options of student count I have for Hogwarts.
My two options are:
1. 100-ish students a year, 25-ish in each house a year, then around 700 students on the whole school.
2. 40-ish students a year, 10-ish in each house a year, then around 300 students on the whole school.
The first option is based on quotes like this:
Harry could hear the drone of hundreds of voices from a doorway to the right — the rest of the school must already be here
(PS, Ch7)
another wave, and the floor was covered with hundreds of squashy purple sleeping bags.
(PoA, Ch9)
Harry could almost feel hundreds of eyes following him as he soared around the field
(PoA, Ch15)
Hundreds upon hundreds of owls of every breed imaginable were nestled here on perches
(GoF, Ch15)
and he could feel hundreds and hundreds of eyes upon him, as though each were a searchlight.
(GoF, Ch17)
Overhead and all around came the elephantine sounds of hundreds of students on the move.
(OotP, Ch12)
And explained further in this post.
*But* this doesn't make sense with other quotes we see that I came across more recently reviewing this topic. For starters, as I mentioned here about the design of Hogwarts school robes, there is no identifying markers of year or house on their robes. It means that whenever Harry mentions "two third-year Hufflepuffs," he says so because he recognizes their faces. Which implies a small student body Harry could reasonably remember the houses and years of everyone by face, if not name.
Additionally, in my post here regarding Hogwarts classes distribution, I've mentioned Gryffindor has DADA alone pre OWLs. Meaning all Gryffindor students of Harry’s year will be present in these classes and no one else. If we look at Lupin's boggart class from third-year, we actually get a list of all Gryffindor students that year.
We can count the students that face the boggart:
R — r — riddikulus!” squeaked Neville. […]
Parvati walked forward, her face set. Snape rounded on her.
There was another crack, and where he had stood was a blood-stained, bandaged mummy; […]
Seamus darted past Parvati.
Crack! Where the mummy had been was a woman with floor-length black hair and a skeletal, green-tinged face — a banshee. […]
Crack! The banshee turned into a rat, which chased its tail in a circle, then — crack! — became a rattlesnake, which slithered and writhed before — crack! — becoming a single, bloody eyeball. […]
Dean hurried forward.
Crack! The eyeball became a severed hand, which flipped over and began to creep along the floor like a crab. […]
Ron leapt forward.
Crack!
Quite a few people screamed. A giant spider, six feet tall and covered in hair […]
Lavender Brown squealed and ran out of its way and it came to a halt at Harry’s feet.
(PoA, Ch7)
The boggart takes 8 forms in front of: Neville, Parvati, Seamus, unnamed Gryffindor girl #1, unnamed Gryffindor girl #2, unnamed Gryffindor girl #3, Dean, and Ron. Then Lavender runs off, not facing the boggart and we know Harry and Hermione don't face it either.
This Lands us at 11 Gryffindor students in Harry's year, and in the range of option number 2, AKA of 40 students a year (which fits the original 40 concept from JKR).
So, currently, I think they have around 10 students per house per year, so there are 4-6 students in a dorm — one girls dorm and one boys dorm per house per year as the books imply.
As we see the sign on Harry's dorm door is just the year:
and at last reached the door of their old dormitory, which now had a sign on it saying SECOND YEARS
(CoS, Ch5)
Meaning there are no other boy dorms in Gryffindor for Harry's year, otherwise, that won't be the sign.
As for the over a hundred tables in the OWLs exams:
He was falling through cold blackness, spinning furiously as he went, and then — He was standing in the middle of the Great Hall, but the four House tables were gone. Instead, there were more than a hundred smaller tables, all facing the same way, at each of which sat a student, head bent low, scribbling on a roll of parchment. The only sound was the scratching of quills and the occasional rustle as somebody adjusted their parchment. It was clearly exam time.
(OotP, Ch28)
Once breakfast was over, the fifth and seventh years milled around in the entrance hall while the other students went off to lessons. Then, at half-past nine, they were called forward class by class to reenter the Great Hall, which was now arranged exactly as Harry had seen it in the Pensieve when his father, Sirius, and Snape had been taking their O.W.L.s. The four House tables had been removed and replaced instead with many tables for one, all facing the staff-table end of the Hall where Professor McGonagall stood facing them.
(OotP, ch31)
We see it's both seventh and fifth years taking their OWLs and NEWTs together. So, it's the students of two years, not one. Harry mentions the Great Hall is identical, meaning there isn't a big difference in the number of tables, if at all. If we go with around 40, maybe even 45 a year, there could be about 80-90 tables there, which is pretty close to a hundred. A quick estimate in a glance of "more than a hundred" is reasonable for 90-ish tables. It's not like Harry is standing there and counting them.
So, yes, it seems there are 40-ish students a year and 10-ish students per house per year, 11 in Gryffindor in Harry's year. That and Harry is pretty bad at estimating the number of people present in large crowds (he's calling a crowd of at most around 300 "hundreds" regularly).
musings on the population size of the wizarding world
I just read the new meta of @hollowed-theory-hall about the population size of the wizarding world. (It's a great meta! Go, read it!) Their essay send me down a rabbit hole, however. While they looked at the size of Hogwarts ... I just stared at ... basically everything else. It got a little bit out of control, lol.
Anyway.
I tried to estimate the size of the workforce of the wizarding world. To do this, I looked at some of the biggest employers that we know of:
the Ministry of Magic
the Quidditch League
St. Mungo's
So let's dissect them.
1. Ministry of Magic
Surprisingly, we have a number for the Minstry of magic. It comes from Goblet of Fire, when Harry and the Weasleys visit the Quidditch World Cup.
“Seats a hundred thousand,” said Mr. Weasley, spotting the awestruck look on Harry’s face. “Ministry task force of five hundred have been working on it all year. Muggle Repelling Charms on every inch of it. Every time Muggles have got anywhere near here all year, they’ve suddenly remembered urgent appointments and had to dash away again . . . bless them,” he added fondly, leading the way toward the nearest entrance, which was already surrounded by a swarm of shouting witches and wizards.
Firstly ... there were a hundred thousand spectators at the World Cup. Welp. A fucking hundred thousand! Where did Rowling pull those numbers from? (Don't answer. We all know the answer and it's a very dark place. It stinks, too.)
Anyway. According to Arthur Weasley, there was a ministry task force that spend a whole year on this quidditch stadium. From the way he phrases this we can assume, that those workers were in the employment of the British Ministry of Magic. Had it been an international task force, he would've said so. So no, those fuckers are Brits.
That said, there is no indication, where those 500 workers come from. It's possible, that all of them worked for the relevant Departments of the Ministry (mostly the Department of International Magical Co-operation and the Department of Magical Games and Sports). It's also possible, that they pulled in employees from other departments. Additionally, they could've hired British and Irish wizards and witches specifically for the event. I assume, it's a combination of those options.
So this only gives us a direction in which to look at, but no final numbers. So let's look at the ministry itself.
We know that the ministry has eight separate departments. Most of them should have at least a few dozen employees.
We know that the Department of Magical Law Enforcement looks something like this: First, there is a corridor that is lined with doors. The Auror Headquarters are at the end of that corridor. Behind the headquarters. there is another another corridor, which then leads to the corridor where Arthur has his office. The Wizengamot Administration Services and the Magical Law Enforcement Patrol are also on this floor, but we don't know their exact locations.
The corridors with their doors imply that there are quite a few bureaus and offices, that we don't know the name of. Each of those has probably at least one employee, probably more.
Then there is the Auror Headquarters. It's a big room that is lined with cubicles. Harry is able to look inside a couple of those. We know, that there are at least 8 aurors working there in 1995 (Dawlish, Robards, Proudfoot, Savage, Shacklebolt, Tonks and Williamson are regular aurors and Scrimgeour as their leader.) From the description of their headquarters, there are probably more of them. (There are quite a lot of cubicles. And it's implied that there are at least a couple of people there, when Harry and Arthur pass through in OotP.)
And that's just the aurors. If we scale this up to the other subdepartments on this level, we're easily talking about 50 to 100 people, here. (My assumptions: The Auror Headquarters has at least eight aurors, but probably more - maybe between ten and twenty. The Patrol should have a similar size, but it might be bigger. Then there are a couple of smaller bureaus that have two to ten employees each - like Arthur's. Then there are the Wizengamot Administration Services. They probably oversee most of this. They might do more mundane administrative work, too, like handing out birth certificates or notarized copies of documents. So they should have at least 10 to 20 employees, too.)
The other departments have probably a similar size (especially the Departments for Magical Accidents and Catastrophes and for Regulation and Control of Magical Creatures.)
If we assume that every department has 50 to 100 employees, we end up with a total work force of 400 to 800 people. The upper estimate would fit Arthur's claim. (At least, if we assume a couple of additional hires.)
2. The Quidditch League
There are thirteen professional teams in Ireland and the UK. Each of those teams should have:
seven main players
reserve players for each position (I would assume that there is at least one reserve player for each position of the team)
a manager, who deals with the ministry and the public
a trainer
a health professional (a healer or someone similar), to heal simple injuries on site and to keep track of each player's health
maintenance staff (at least two workers, one to take care of the equipment and one for the quidditch pitch)
security personnel (it's possible that the ministry provides some or all security personnel needed - but that would increase the number of employees the ministry has)
one or more workers who sell and control tickets
one or more workers who sell merchandise
some workers who sell food and goodies during games
Including players, each team should have about 20 to 30 workers - probably more, if the team has to provide at least some security staff. So we're talking about at least 260 to 390 people, here.
3. St. Mungo's Hospital for Magical Maladies and Injuries
This seems to be the only hospital for the wizarding populace. At the same time, the hospital seems quite large for the populace it has to support.
It's stated in OotP, that "Nowhere in Diagon Alley was big enough", so they use "a large, old-fashioned, red brick department store" in a muggle neighborhood instead. It has six floors, five of which are used to treat patients. We see some of those, when Harry and Co. visit Arthur in OotP.
First, they pass through the reception area that is located on the ground floor. There, we have the following description:
Witches and wizards in lime-green robes were walking up and down the rows, asking questions and making notes on clipboards like Umbridge’s. Harry noticed the emblem embroidered on their chests: a wand and bone, crossed.
There are "witches and wizards" walking up and down the rows of patients. The wording suggests that there are at least four of them: Two witches and two wizards. (Otherwise, the narration wouldn't use the plural forms to describe them.) Their lime-green robes and their emblem identifies them as healers.
In addition to them, there is also a welcome witch at the reception desk.
While they wait in line, a wizard further up the line asks the welcome witch where to find Broderick Bode. She informs him that Bode is on ward forty-nine. (This ward is later specified to be the Janus Thickey ward.)
She doesn't specify the floor, so there is probably only one "ward forty-nine" in the hospital. Considering that ward forty-nine is on the fourth floor, there might be about 50 wards total, ten on each floor.
After they speak to the welcome witch, Harry and Co. proceed to the first floor:
They followed through the double doors and along the narrow corridor beyond, which was lined with more portraits of famous Healers and lit by crystal bubbles full of candles that floated up on the ceiling, looking like giant soapsuds. More witches and wizards in lime-green robes walked in and out of the doors they passed; a foul-smelling yellow gas wafted into the passageway as they passed one door, and every now and then they heard distant wailing. They climbed a flight of stairs and entered the “Creature-Induced Injuries” corridor, where the second door on the right bore the words “DANGEROUS” DAI LLEWELLYN WARD: SERIOUS BITES. Underneath this was a card in a brass holder on which had been handwritten Healer-in-Charge: Hippocrates Smethwyck, Trainee Healer: Augustus Pye.
This quote gives us even more information. The group probably passes the wards and treatment rooms on the ground floor (Artefact accidents), here. They see more healers on their way. (The quote talks about "witches and wizards" again, so there seem to be at least four here, too.)
They then reach the first floor. This floor is split into (specialized) wards. The Dai Llewellyn ward has a healer-in-charge and a trainee. This implies that there are multiple healers (and probably multiple trainees, too) on each level. Otherwise, the specification wouldn't be needed. However, this doesn't give us a total number. It's possible, that each ward has their own healer-in-charge. At the same time, a healer might be healer-in-charge for multiple wards, too.
Using this as a foundation, I assume the following:
there are multiple healers-in-charge on each level, at least two or three, but up to ten (depending on whether or not a healer can be healer-in-charge for multiple wards or not)
during consultation hours, there are at least four healers working on each level to take care of incoming patients
during consultation hours, there are at least four additional healers working in the reception area
there are at least two or three healers on each level all the time, including nights, weekends and holidays (There job is to watch over the patients and to take care of any emergencies)
there might be additional healers who can be sent out to emergencies (like first responders and emergency doctors)
they work in shifts (there is probably an early shift, a late shift and a night shift. There might be an additional shift for consultation hours)
there is additional personnel for administrative work and for the visitor's tearoom and the hospital shop
St. Mungo's might be specialized potion masters in addition to its healers
there should be a kitchen, too, but we don't know whether it's staffed by humans or house elves (the same applies to cleaning staff)
I would assume that the absolute minimum of wizards and witches working at St. Mungo's is about 50. However, each healer will probably only work five or maybe six days a week. They should also have some paid vacation days. This will cause the numbers to go up. If there is an extra shift for consultation hours, this will cause numbers to rise, too. As would a specialized time of first responders/emergency healers or a team of potion masters. Considering that there is at least one trainee healer, there might be a whole training program - which would have both trainees and educators. Then there is the administrative staff and maybe kitchen and cleaning staff.
In total, we're probably looking at 100 to 150 workers for the hospital. (This will also depend on how heavily the hospital relies on slave labor in the form of house elves.)
An additional point I want to make here: The reception area was packed, when Harry and the others visited Arthur. Like, there were easily a few dozens people in the reception area alone! (Otherwise, they would not need multiple healers to check on the patients there.) Either, wizards get injured pretty often or the wizarding population is bigger than expected.
This leaves us with at least 710 to 1,340 works in those fields alone. That's quite a lot of people - especially when we consider that the wizarding world only has a few thousand or ten thousand inhabitants.
(At the same time - Rowling sucks at maths, so who knows.)
Do the math, there are way too many wizarding children in the United States for Illvermorny to support on its own. Okay wait, math is perhaps not the right way to peak your interest. But let’s do the math quickly anyway. Stick with me, the magic is coming.
It is extremely difficult to accurately estimate the population of the wizarding world, partially because we have conflicting numbers from JK Rowling herself. She has said (in an interview with Scholastic from 2000) that she estimated the population of Hogwarts while Harry was there to be around 1,000 students. Assuming that there are a few students that are sent to the European continent or schooled at home, and that (as in current estimations) the percentage of Hogwarts-age students is ~11% of the total population, that would give us a wizarding population in the UK of somewhere in the range of 12,000-13,000.
If we apply the same proportions of magic/muggle (.0003%) to the US population, we get a US magical population of somewhere around 96,400. Recent census data tells us that in the United States, around 13% of the population is Hogwarts-aged, giving us a magical school population of 12,500.
However, JK Rowling has also said that there are ten times more Muggles than there are wizards in the world which would give us something more like 32 million wizards in the United States and 417,000 school-aged kids. There’s a big difference between 417 thousand and 12 thousand but either way, there are just way too many students for one school, roughly the size of Hogwarts, to accommodate. At the low-end of the estimates, you need around 10-12 schools to properly educate the number of wizarding kids in the country, at the high end, you might need several hundred.
So imagine for a second, what do all of those schools look like? Where are they hiding from the eyes of muggles, what are their educational emphases? Their history? Who founded them, who attends them? What kinds of spells or magical inventions have come out of them? Who teaches the wider magical world?
For the sake of argument, this blog is going to assume that the magical world needs more schools, that specifically the US needs more wizarding schools. So let’s make them. Together. That’s the project of WizardEdu.
So, I wrote about this subject in the past (here and here), and I was of the belief the Wizarding World is pretty small (~300 students at Hogwarts, ~6,200 wizards in the UK). However, I wanted to challenge my own notion with book evidence that there are more students at Hogwarts in Harry's time, working under the assumption that there are more students in Harry's year we just never hear about.
I was somewhat inspired by this post by @perilousraven that calculated the capacity of the coaches that take the students up to the school. As I wanted to revisit my estimates on the wizarding population and Hogwarts population anyway, I decided to calculate the capacity of the Hogwarts Express to see if it matches the stagecoaches' capacity. Plus bringing up book evidence that my estimate for the Hogwarts population was low but I was correct about the size of the overall wizard population due to their distribution by age being different than in my earlier posts (a case of the "math was wrong but the result was right-ish").
So, let's start with evidence that there are more than 280 students at Hogwarts:
“No more’n four to a boat!” Hagrid called, pointing to a fleet of little boats sitting in the water by the shore.
(PS)
4 in a boat for 40 students will be 10 little boats. I'm not sure if Harry would call that a "fleet". Technically it could be considered a fleet, but I think there would be more boats for Harry to refer to it as a "fleet".
They followed Professor McGonagall across the flagged stone floor. Harry could hear the drone of hundreds of voices from a doorway to the right — the rest of the school must already be here
(PS)
Professor McGonagall led the first years up here, so that they came to a halt in a line facing the other students, with the teachers behind them. The hundreds of faces staring at them looked like pale lanterns in the flickering candlelight.
(PS)
Harry left the castle and set off in the dusk toward the Quidditch field. He’d never been inside the stadium before. Hundreds of seats were raised in stands around the field so that the spectators were high enough to see what was going on.
(PS)
But it was too late. A rumble, as though of distant thunder, told them that the feast had just ended. From either end of the corridor where they stood came the sound of hundreds of feet climbing the stairs, and the loud, happy talk of well-fed people; next moment, students were crashing into the passage from both ends.
(CoS)
One casual wave of his wand and the long tables flew to the edges of the hall and stood themselves against the walls; another wave, and the floor was covered with hundreds of squashy purple sleeping bags.
(PoA)
Harry got to his feet, trod on the hem of his robes, and stumbled slightly. He set off up the gap between the Gryffindor and Hufflepuff tables. It felt like an immensely long walk; the top table didn’t seem to be getting any nearer at all, and he could feel hundreds and hundreds of eyes upon him, as though each were a searchlight.
(GoF) - when Harry is chosen as a champion
He was falling through cold blackness, spinning furiously as he went, and then — He was standing in the middle of the Great Hall, but the four House tables were gone. Instead, there were more than a hundred smaller tables, all facing the same way, at each of which sat a student, head bent low, scribbling on a roll of parchment. The only sound was the scratching of quills and the occasional rustle as somebody adjusted their parchment. It was clearly exam time.
(OotP)
more than a hundred seats, but they are both fifth and seventh years:
Once breakfast was over, the fifth and seventh years milled around in the entrance hall while the other students went off to lessons. Then, at half-past nine, they were called forward class by class to reenter the Great Hall, which was now arranged exactly as Harry had seen it in the Pensieve when his father, Sirius, and Snape had been taking their O.W.L.s. The four House tables had been removed and replaced instead with many tables for one, all facing the staff-table end of the Hall where Professor McGonagall stood facing them.
(OotP)
So the over a hundred we see above in SWM is both seventh and sixth years, meaning each year in the Mauraders' generation is about 70 students, so then we'd have ~110-120 students in the Great Hall in the exam in SWM. Since not all 7th-years are taking the NEWT exam in DADA, I assume most of these students are 5th-years.
“I would like each of you to place yourselves now so that you
have a clear five feet of space in front of you.”
There was a great scrambling and jostling as people separated,
banged into each other, and ordered others out of their space. The
Heads of Houses moved among the students, marshaling them
into position and breaking up arguments.
“Harry, where are you going?” demanded Hermione.
But Harry did not answer; he was moving quickly through the
crowd, past the place where Professor Flitwick was making squeaky attempts to position a few Ravenclaws, all of whom wanted to be near the front, past Professor Sprout, who was chivying the Hufflepuffs into line, until, by dodging around Ernie Macmillan, he managed to position himself right at the back of the crowd, directly behind Malfoy, who was taking advantage of the general upheaval to continue his argument with Crabbe, standing five feet away and looking mutinous.
(HBP) - when the 6th years are taking the apparition exam they are a considerable crowd
When Harry describes the Great Hall or a crowd of the entire school, he's talking in the hundreds. The above phrasing would be odd if the "hundreds" talked about are 3 max. So, the implication is that there are more students, probably not a thousand, but closer to it.
Now, I wanted to know what number of students we're talking about, so I could have an estimate of the population size. There are two available avenues:
A hundred horseless carriages stood waiting for them outside the station. Harry, Ron, Hermione, and Neville climbed gratefully into one of them, the door shut with a snap, and a few moments later, with a great lurch, the long procession of carriages was rumbling and splashing its way up the track toward Hogwarts Castle.
(GoF)
A hundred (or over a hundred in PoA) coaches to the school only for the older years, plus the boats for the first years. In the post I linked above from perilousraven calculated the capacity would be for 700 students or more at the school (I think the estimate of the older, smaller coaches is probably closer to the case in the books and would work with what the Hogwarts Express would allow).
But I wanted to look at the Hogwarts Express, as well, to see if we get a different number of students or if we're around the same estimates since the train should have all students, including first-years traveling by it:
They struggled off down the corridor, peering through the glass-paneled doors into the compartments they passed, which were already full. Harry could not help noticing that a lot of people stared back at him with great interest and that several of them nudged their neighbors and pointed him out. After he had met this behavior in five consecutive carriages he remembered that the Daily Prophet had been telling its readers all summer what a lying show-off he was. He wondered bleakly whether the people now staring and whispering believed the stories.
In the very last carriage, they met Neville Longbottom
(HBP)
So we have at least 6 passenger carriages (potentially more if we're talking about a newer 20th-century steam engine, which I assume we are since the earlier Victorian ones only had up to four carriages).
Now, there might be a 7th perfect carriage:
“We’re — well — Ron and I are supposed to go into the prefect carriage,” Hermione said awkwardly.
(OotP)
But earlier Percy mentions Prefect compartments:
“Can’t stay long, Mother,” he said. “I’m up front, the prefects have got two compartments to themselves — ”
(PS)
So, we have at least 6 regular carriages and another carriage just for the prefects' compartments and the large compartment Slughorn used for the slug club (possibly he used a prefect compartment, as I assume that first car is designed differently).
(I will note the prefects have a place to sit on the train (Ron and Hermione rejoin Harry later in OotP) and we see Lupin has a place to sleep on the train in PoA:
This had only one occupant, a man sitting fast asleep next to the window. Harry, Ron, and Hermione checked on the threshold.
(PoA)
Although the train is apparently "full":
Harry, Ron, and Hermione set off down the corridor, looking for an empty compartment, but all were full except for the one at the very end of the train.
(PoA)
So, while all compartments are usually in use, there are likely quite a few that aren't completely full but still don't have a place for 3 more students.
Now, the number of carriages varied a lot throughout the years. The early steam engines that were around when the Hogwarts Express was first established (circa the 1830s) were weak and the trains were pretty small, only carrying at most 4 smaller carriages most of the time (either when the Hogwarts Express was established there were way fewer students or there was more than one train). In the early 20th century we see Express trains with stronger engines (such as the Flying Scotsman) that would regularly carry 8-12 carriages but could carry up to 14 on busier days. So, let's say the Hogwarts Express has 13 regular carriages and another prefect carriage that isn't part of this calculation for the reasons mentioned above.
Each carriage is divided into compartments with 6 people fitting per compartment:
Too soon, it was time for the journey home on the Hogwarts Express. Harry, Ron, Hermione, Fred, George, and Ginny got a compartment to themselves.
(CoS)
This gives an idea of the layout (with a large enough corridor for the trolly lady):
(Using diagrams from the Flying Scotsman which is my closest analog)
Which lands us with 7 compartments per carriage. That being said, as Harry says this:
Firstly, Malfoy, Crabbe, and Goyle, who had clearly been waiting all week for the opportunity to strike without teacher witnesses, attempted to ambush Harry halfway down the train as he made his way back from the toilet.
(OotP)
This implies only the first carriage has a toilet (the prefect carriage), which seems weird to me since you have a few hundred students on that train for around 9 hours. But, the books imply there is only one toilet at the first carriage (maybe it's more than one stall. I hope it's more than one stall), so the train cars would look slightly different from the ones above —two more compartments and everything shifted a little to the side to accommodate. There will be one less door leading outside from such a carriage and slightly narrower compartments (which did exist, there were 6-person train compartments that were 6'1 wide instead of the pictured-above 6'6. These cars came with a toilet though so I edited the above picture. Why do they only have a toilet in the first compartment? Makes no sense):
9 compartments * 6 students * 6 cars = 324 for the minimal amount of space for students on the train.
9 compartments * 6 students * 13 cars = 702, which is spot on to the lower stagecoach estimate of about 700 students at max capacity of the train.
Potentially even more seats would be available if the prefects' carriage is sometimes replaced by a regular carriage (with a toilet) when there are more students. This would explain why Percy described two prefect compartments in PS, but in OotP and HBP the prefects have a whole carriage. This extra car will give us space for another 48 students. The fact they needed to remove the prefect carriage in PS to allow more space for students suggests Hogwarts was practically at its full capacity in 1991. (And that in 1995 there were ~50 less students in the school than in 1991)
So, at the maximum capacity (which seems to be the case in most of the books), the train is pretty much in the range of @perilousraven's stagecoach estimate.
So, what does it change about my estimates of the wizarding population? Not much actually.
Let's say there are around 700 students at Hogwarts when Harry is there (700 makes sense, it's 7 and it divides nicely, it's a round and pretty number. A little lower than the stagecoach estimate, but it makes more sense with the train. I actually think for most of his years it's a little less than 700, but I like round numbers):
700 students at the school -> 100 students per year -> 25 students per house per year -> 175 students per house.
(This also means Harry has more of an excuse not to know people in his year)
Which leads to the distribution of the population to be something like this approximation (The percentages are loosely based on 1992 UK population distribution by age, adjusted so there will be higher percentages for 90+ people due to the supposed longer lifespan of wizards and I made the generations born in the 1970s larger in percentage due to the first war's baby boom. Note that the number per house/year is inaccurate in the older generations since they're dying out):
(The percentages above are rough estimates cause I hate math and I like round numbers)
This keeps us at a wizarding population of about 6,000 wizards in the UK and Ireland (in the range of my former estimate of 5,700 - 6,200).
My former estimates were made with an adjusted distribution by age I explained here and here, due to the wars in the wizarding world being a little different from the muggle one, but I think that former distribution is wrong. I disagree with my past self on that, hence why I'm making this post and will edit a link to it in the relevant former theories. I came to the conclusion Harry's generation is actually one of the larger ones and that their population is younger. After all, most of his grandparents' generation is dead. The 1980s came right after Voldemort's defeat — so it's likely it brought a baby boom with it. Additionally in the 1970s (especially the latter half), we see couples marrying young and having children young (Arthur & Molly, James & Lily, probably Frank & Alice, and others) and we see this pattern of marrying during the war happening again in 1997-1998. So, I think the war years will also come with a baby boom compared to the generation of the Mauraders. Which, all in all, is closer to irl UK population distribution in the early 1990s.
So, my estimate now is still at around 6,000 wizards in the UK and Ireland (a bit less than 0.01% of the population) in the 1990s and 700 of them are at school with Harry since his generation is actually the largest one presently.
(Unfortunately, this changes some of my older percentages and estimates. It means that less than 5% of wizards in the UK are muggleborn and that below 12% of students get Os in most OWL exams, for example. Though, luckily the population remains in my former estimate range so it doesn't change everything. So I might slowly go back to add edit comments. I'm not planning to rewrite them for now, but just to add a little comment about this.)
So, this is not like 100% finished and will be more musings than a full theory. The main reason is that we, as humanity, just don't really know that much about genetics. Like, we get the gist of it, but we can mostly only say: "it's complicated" about it.
Which is true. Like, the idea of dominant and recessive traits the way most people are familiar with (like the eye color chart for blue eyes and brown eyes) is super oversimplified and inaccurate. Like, there are 2 major genes that affect eye color and then there are 8 more genes that affect eye color, hair color, and skin color, but we aren't really sure in what way. We just think they do from observation. Usually, genes behave in a way that is in line with the dominant and recessive traits charts, but there are exceptions to it. Again, we just don't know much about this field.
Because of this, I can't really come to conclusive conclusions regarding exactly how many and which genes affect a person's magic in the world of Harry Potter. What I can do is use the book evidence to try and create a pattern of how magic behaves genetically.
Disclaimer: I'm not a doctor, nor did I study genetics in any professional capacity, this is from online reading and self-study. And most importantly for fun 😊
Why do I think magic is influenced by multiple genes?
So, JKR stated in an interview she thinks of magic as a single dominant gene. This is impossible, since if that were true squibs and muggleborns wouldn't exist and the chart for the likelihood of a child being born with magic would look like this:
And that's just not what we see in the books...
This is all without mentioning how squibs like Arabella Figg can see dementors while muggles can't:
“A Squib, eh?” said Fudge, eyeing her suspiciously. “We’ll be checking that. You’ll leave details of your parentage with my assistant, Weasley. Incidentally, can Squibs see dementors?” he added, looking left and right along the bench where he sat.
“Yes, we can!” said Mrs. Figg indignantly.
(OotP, page 143)
This means that squids do have some magical genes that muggles don't.
Additionally, from what we know about wizards as a species they have other differences from muggles that would effect their genetics in less obvious ways, for example:
Wizards heal faster, so cell regeneration is different than muggles.
Wizards have a completely different set of illnesses than muggles, so their white blood cells are also different.
Their brain cells likely live longer since they have an overall longer life expectancy.
Since they can see magic, like dementors and the Leakey Cauldron, we know the sight receptors are different.
Their nerves likely also function differently since they can sense magic in a way muggles can't.
To name a few.
And this is all without going into the fact wizards can reproduce with other species (goblins, veela, and giants to name a few) which actually implies a common ancestor to all of these races, but I'm not going into that can of worms.
What I am going into is how magic works genetically and how predictable it is. As in, if I know the magical status (pure-blood wizard, half-blood wizard, muggleborn wizard, squib, or muggle) of two human parents, can I tell how likely their child is to be a wizard, a squib, or a muggle?
What are squibs?
We don't know of many squibs in the books, these are the list of the known squibs:
Argus Filch
Arabella Figg
Marius Black
Dolores Umbridge's brother
Molly Weasley's second cousin
Squibs aren't a subject wizards like talking about, even not wizards who don't mind muggles like the Weasleys:
"Er — yes, I think so. I think Mum's got a second cousin who's an accountant, but we never talk about him."
(PS, page 73)
The definition of a squib is a child without magic born of a magical parent. If we look at the list of squibs above, all of them except Umbridge's brother are pure-bloods. This is kind of important because of the limited genetic pool of pure-bloods.
I tried calculating the inbreeding coefficient (basically how likely it is that a specific genetic trait is identical in both parents. The number ranges between 0 and 1) of the pure-bloods in the Wizarding World. We don't have much information on most families, but even looking at the Black family tree, they aren't really inbred (except the Gaunts). The closest relation there is the marriage between second cousins Walburga and Orion. So the inbreeding coefficient of pure-bloods would be above zero, but not high enough to cause serious health detriments for the most part. But, this doesn't mean wizards don't have a problem with a limited genetic pool even without close inbreeding.
Looking at that same Black family tree, we see a lot of familiar names: Flint, Crabbe, Burke, Potter, Crouch, Longbottom, Weasley, Prewett, Malfoy, McMillian... Basically, all pure-blood wizards are related. Some more closely than others, but they are all related. It means that among pure-bloods there is less genetic diversity which tends to cause illnesses and weakness in children over the course of multiple generations.
Such illness can, for example, come in the form of a squib. If the child just isn't capable of having full access to magic, due to their limited genetic pool, they will be born a squib.
But what about Umbridge's brother?
Well, here's the interesting thing. When looking at accounts of children of a pure-blood and a muggleborn, they are all always magical (and usually quite powerful, but more on that later). Umbridge's mother though is muggle. I believe a muggle parent would also have a higher chance of a squib offspring since they don't have magic. Essentially, Umbride's brother received some of the magical genes from their father, and some muggle genes from their mother, leaving him somewhat capable of interacting with magic, but not casting it — a squib.
Essentially squibs have a higher chance to be born from two pure-bloods (due to lack of genetic diversity) or from a wizard and a muggle. If we look at the books, we actually never see a squib being born from a pair of two wizards where one of the parents is half-blood or muggleborn (since they bring new genetic diversity and make the offsprings much likelier to be magical).
What are muggleborns?
So, we covered that squibs are rare and are caused by the lack of genetic diversity in the pure-blood families or by receiving non-magical genes from a muggle parent. But what about muggleborns? How could they genetically exist?
Well, I discussed here the actual percentages of different blood statuses across the Wizarding World. And the percentages looked like this:
57.5% Pure-Blood and Most Likely Pure Blood
22.5% Half-Blood
15% At Least One Magical Parent
5% Muggleborn
And as I covered here and here, I believe magical Britain is approximately 0.01% of the muggle population. This means that muggleborns are incredibly rare in the muggle population and have an overall very low chance of being born. But under what circumstances would muggleborns be more likely?
We know, for example, that the brothers Colin and Dennis Creevey were both born magical. It means, that their parents had genes that make them more likely to have magical children. This means Petunia had a higher chance of being born magical than, say, Vernon, it was still a low chance, but it was more likely.
Now, I'm not the first to raise this theory, but I believe these muggles that have a slightly higher chance for magical children like Mr. and Mrs. Creevey are descendants of squibs. We know that:
"Squibs were usually shipped off to Muggle schools and encouraged to integrate into the Muggle community. . . much kinder than trying to find them a place in the Wizarding world, where they must always be second class..."
(DH, page 136)
So, squibs have been sent for generations to live among muggles. It means that there are multiple "muggles" running around that are actually squibs. They might be able to see dementors or notice something odd around the Leakey Cauldron, but not enough to produce magic. But they still have magic in their genes. And when they have kids, sometimes, through a fluke of luck and genetics a muggleborn can be born.
This means all muggleborns are distantly related to wizards in some way, but still the muggle blood adds some much-needed genetic diversity that makes them less likely to have squib children.
What would magical genes look like?
So, we talked so far about how to predict the likelihood of a child having magic or not. But we also know not all wizards and witches are magically equal. You have crazy powerful individuals like Voldemort, Harry, and Dumbledore. Hermione is an incredibly skilled and talented witch, often the first in class to get spells right. And then you have wizards like Crabbe, Goyle, or Merope who are barely more magical than squibs. Then you have unique magical gifts like being a parselmouth, metamorphmagus, or seer are all inherited, and therefore genetic.
So, let's start with the power/talent difference between wizards that we see. I think this, like squibs, is correlating to the lack of genetic diversity. Sure, you have pure-bloods that are magically powerful or average, but if we look at the most magically powerful wizards in the books — Harry, Voldemort, and Dumbledore — they are all half-bloods. They all have a higher genetic diversity.
Hermione and Lily, are also examples of this added genetic diversity raising the likelihood of magical talent. Both muggleborns, both referenced as talented and bright multiple times. Snape, another half-blood is also referenced often as an incredibly talented wizard.
Actually, Nymphadora Tonks is one of the best pieces of evidence for magic weakening over pure-blood generations and becoming stronger with the new blood from muggles or muggleborns.
The Black family had the hereditary magical gift of being metamorphmagi. This gift has been lost for multiple generations, the first Black to be born with this gift in recent history is Tonks. And it makes perfect sense, Andromeda, a pure-blood with the genes for being a metamorphmagus, marries a muggleborn, Ted, who has the much-needed genetic diversity, so their daughter is finally durable enough for the metamorphmagi magic to kick in.
The Gaunts are another example of just how much the lack of genetic diversity affects a wizard's magic. All three, but especially Mereope, are portrayed as barely skilled with magic, almost squibs. But then we have Tom Marvolo Riddle, magically gifted so much beyond most wizards because he had the added genetic diversity from his muggle father.
Parseltongue seems to be a more dominant trait than the metamorphmagus ability. As even an almost squib in the Gaunt family can speak it. That being said, the Gaunts are implied to be incredibly incestuous, so perhaps it's just a matter of both parents speaking Parseltongue that causes this gene's apparent dominance.
We also know these genetic traits are only passed to wizards. So a squib from the Gaunt family, would not be able to speak Parseltongue. So, while it is a separate gene, it is connected to the other genes that affect magic. That's why a muggleborn born from a Gaunt family squib line, could potentially be a Parselmouth. They won't necessarily be a Parselmouth, but they have a chance to get the gene.
Conclusions
So, let's put all of it together into a series of rules* to how magic seems to work genetically.
*Rules is not exactly the correct word. It's more like, how it would usually behave, but there are flukes to genetics and everything is possible.
Two magical parents would almost always have a magical child. Pure-bloods are more likely to have squib children than half-bloods or muggleborns due to lack of genetic diversity.
A child of a muggle and a wizard has a higher chance of being born a squib than two magical parents. (The chance is still pretty low though and the child is more likely to be magical)
Muggleborns are the result of at least one parent who is a muggle that descended from squibs and has magical genes.
If both parents are squib-descendant muggles, all their kids might even end up magical. (Like the Creevey brothers)
Being a parselmouth, metamorphmagus, or seer are all unique genetic traits that are passed in a separate gene but dependent on other magical genes. Each one of them behaves differently as a gene.
Genetic diversity promises a higher chance of naturally magically gifted children. (It doesn't promise they will be more gifted, just makes their chances better)
Blood purity and a limited genetic pool cause magical children born to these lines to be overall weaker. (Again, there are exceptions, this is just about chances)
How many muggleborns actually are there in the UK?
So, I think, the first thing I post here should be what started my HP theorizing journey. Which was an IRL friend asking me how many muggleborns even are there in the Wizarding World to cause this much strife?
So strap on in for a journey of demographic statistics and me documenting every name in the book and their blood status like someone who actually cares (I don't, but I do have some things to say about blood status, inbreeding, and magical genetics, but that's a whole different post)
So, when I started thinking about how to figure out what percentage of muggleborns are in the British Wizarding World, I decided to start simple. Harry's year (according to JKR's notes and Harry Potter and Me) has 40 students. Fewer are mentioned by name in the books, but I created the closest approximation on these 40 students according to book information and notes from JK.
(In general, book canon precedes any other source)
Harry's year is a good start since it gives us a look at all wizards and witches born in the UK in the same year, as it seems all Hogwarts years are similar in size. So this is a good enough rough approximation of blood status across the wizarding world in the UK as a whole (and the one we have the most information about).
Some definitions about blood status and the way it seems to be treated in the books so we'll all be on the same page:
Muggleborn - a wizard with two muggle parents
Pure-Blood - a wizard with two magical parents of which none are muggleborn and at least one is pure blood (i.e a child of a half-blood and a pure blood would be considered a pure blood for this list)
Half-Blood - Only one magical parent who isn't a muggleborn
At least one magical parent - a character we knew for sure isn't muggleborn but do not have further information.
So without further ado, here are the 40 wizards in Harry's year:
In Gryffindor:
Harry Potter - Half-Blood - Book text
Ronald Weasley - Pure-Blood - Book text
Dean Thomas - Half-Blood - Book text
Seamus Finnigan - Half-Blood - Book text
Neville Longbottom - Pure-Blood - Book text
Hermione Granger - Muggleborn - Book text
Praviti Patil - Most Likely Pure Blood - In book 1, Praviti and Pansy Parkinson are shown to be on a first-name basis and familiar from before Hogwarts. I don't see the blood purists Parkinsons being acquainted with who they consider "lesser blood".
“Ooh, sticking up for Longbottom?” said Pansy Parkinson, a hard-faced
Slytherin girl. “Never thought you’d like fat little crybabies, Parvati.”
- Philosopher Stone, page 108
Lavender Brown - Pure-Blood - According to Harry Potter and Me Notes.
In Slytherin:
Millicent Bulstrode - Most Likely Pure Blood - due to the Bulstrode family appearing in the Sacred Twenty-Eight. (I'm aware in JK's notes mentioned in Harry Potter and Me, Millicent is described as a half-blood, but as many of the characters there didn't make it into the book, they are less canon than the book information)
Vincent Crabbe - Pure-Blood - Book text
Tracy Davis - Half-Blood - According to Harry Potter and Me Notes.
Gregory Goyle - Pure-Blood - Book text
Daphne Greengrass - Pure-Blood - The Greengrass family appears in the Sacred Twenty-Eight
Draco Malfoy - Pure-Blood - Book text
Theodore Nott - Pure-Blood - The Nott family appears in the Sacred Twenty-Eight (Nott's grandfather/great-grandfather is also the most likely to have written it)
Pansy Parkinson - Pure-Blood - The Parkinson family appears in the Sacred Twenty-Eight
Blaise Zabini - Pure-Blood - Book text
In Hufflepuff:
Hanna Abbott - Pure-Blood - The Abbott family appears in the Sacred Twenty-Eight
Susan Bones - Most Likely Pure Blood - Mentioned to have multiple magical relatives including Amalia Bones (Head of the DMLE) a prominent figure in the incredibly corrupt Ministry of Magic that practically runs on nepotism (a subject fro a different post, probably).
Justin Finch-Fletchley - Muggleborn - Book text
Wayne Hopkins - Half-Blood - According to Harry Potter and Me Notes.
Megan Jones - Most Likely Pure Blood - Mentioned to have multiple magical relatives (even if the wiki calls them half-bloods, there are a lot of wizards from this family).
Ernest Macmillan - Pure-Blood - The Macmillan family appears in the Sacred Twenty-Eight
Zacharias Smith - Most Likely Pure Blood - As someone who brags of being a descendant of Helga Hufflepuff and being able to trace magical lineage so far back.
In Ravenclaw:
Terry Boot - At Least One Magical Parent - As he goes to Hogwarts during the 1997-1998 school year when muggleborns were forbidden from doing so.
Mandy Brocklehurst - Half-Blood - According to Harry Potter and Me Notes.
Michael Corner - Half-Blood - According to Harry Potter and Me Notes.
Stephen Cornfoot - Pure-Blood - According to Harry Potter and Me Notes.
Anthony Goldstein - Half-Blood - According to Harry Potter and Me Notes.
Sue Li - Half-Blood - According to Harry Potter and Me Notes.
Morag MacDougal - Pure-Blood - According to Harry Potter and Me Notes.
Padma Patil - Most Likely Pure Blood - Same as Praviti Patil.
Lisa Turpin - At Least One Magical Parent - Most likely. This is a character nothing is stated about, but I assume that if she was muggleborn it would have been mentioned during the second war.
Unknown House:
Oliver Rivers - At Least One Magical Parent - Same reasoning as Lisa Turpin.
Roger Malone - At Least One Magical Parent - Same reasoning as Lisa Turpin.
Lily Moon - Most Likely Pure Blood - Has other magical relatives of the name Moon across HP media.
Sally-Anne Perks - At Least One Magical Parent - Same reasoning as Lisa Turpin.
Sophie Roper - At Least One Magical Parent - Same reasoning as Lisa Turpin along with other wizards with the same surname.
Runcorn - Most Likely Pure Blood - As she is likely related to Albert Runcorn who worked in the Ministry of Magic under the Death Eaters' rule and worked as an intimidator and blackmailer of alleged muggleborns.
Sally Smith - Most Likely Pure Blood - As she is likely related to Zacharias Smith.
From this we see that we have:
23/40 = 57.5% Pure-Blood and Most Likely Pure Blood
9/40 = 22.5% Half-Blood
6/40 = 15% At Least One Magical Parent
2/40 = 5% Muggleborn
This kind of percentage is one we see among the Order of the Phoenix (another group of wizards who accept muggleborns and we have information about their blood status) as well. So, it's not just Harry's generation that is low on muggleborns, but that muggleborns are a very small percentage of the wizarding population.
At the Order's peak in members during the First War (therefore before most potential mass muggleborn killings) it had 25 members, and I'll make this list shorter:
Pure-Blood: 8/25 = 32%
Alastor Moody, Alice Longbottom, Elphias Doge, Fabian Prewett, Frank Longbottom, Gideon Prewett, James Potter, Sirius Black
Most Likely Pure Blood: 6/25 = 24%
Dedalus Diggle, Edgar Bones, Emmeline Vance, Marlene McKinnon, Peter Pettigrew, Sturgis Podmore
Only one of the Order members is a muggleborn - Lily Potter.
The fact that even among a group like the Order of the Phoenix (who fought against Voldemort and blood-purists) we see practically no muggleborns just proves the above statistics in Harry's year are the norm. There is probably one or two muggleborns who arrive every year at Hogwarts and they are, overall, a very small present of the population.
This is kind of interesting to me in terms of how much of an issue their very existence is made to be for some wizards in the books, and I thought I should share it since I never see anyone doing maths to calculate population statistics and demographics for the Wizarding Wolrd.
At some point, I should post about the death rates of the two wars with Voldemort along with other stats and timelines I've calculated.
sorry if you’ve already answered something like this but given that we have a few different answers in canon, how many students do you see Hogwarts having? given their actual class sizes and lack of professors per subject i’d say the usual answer of roughly 10 kids per house per year makes sense. except Harry doesn’t know who Mclaggen is until he introduces himself which makes JKR’s statement of 1000 kids in school seem more likely because if there are only 40-ish kids in Gryffindor there’s no reason for Harry to have never seen someone in the year above him for the last 6 years right?
Hi, no problem. I have actually written about this before both here and here. And I tend to disregard JKR's statements outside of the books when they contradict the actual text. I'm a big advocate of death of the author so if the books imply something and Pottermore/JKR implies another, the book evidence takes precedence.
Even if Hogwarts has around 300 students (40 per year X 7 years brings us to 280) 11 professors with one teacher per subject is still an incredibly low student-teacher ratio. I also tried to create a schedule that could work with one professor per subject and 7 years, divided into two classes per mandatory non-NEWT subject (electives and NEWT classes have all 4 houses present but I believe 4th year Transfiguration, for example, is divided into 2 classes because all the 40 students are studying it), and I found that each student would only have about 20 class hours a week, which is pretty low. So unless all the professors are using time turners or there are more professors we don't know about I don't think the number of staff could support a student body much larger than 300. It also means Hogwarts students have so much free time that really all the homework is reasonable, tbh. (Maybe I should write about Hogwarts' schedule and homework amount at some point...)
As for Harry not noticing McLaggen... Harry has students in his own year in Gryffindor he doesn't notice. There are likey 2 other girls in Hermione's dorm besides Praviti and Lavender that he never mentions (I believe these are Sally-Anne Perks, who is sorted in book 1, and Sophie Roper who is in JKR's notes about Harry's year). Harry just tends to be very selective with the information he chooses to pay attention to and note to the reader. Like, if he has no reason to care about McLaggen he won't bother noticing him. So, that doesn't necessarily mean anything.
I mention it in the posts I linked regarding the size of the Wizarding Population in the UK, but I believe the size of the population we see in Harry's generation is slightly decreased from former generations and that the population would grow back after the books. This is due to fewer births (we see more only children than in former generations) and less to do with actual deaths in the war, which I covered in the first linked post too.
Okay. So, the population of the UK in 1980 was 56.31 million.
If muggle born wizards are .1% of the recorded population, that would be
56,310,000 * 0.001 = 56,310
56,310 muggleborns in 1980. Assuming that muggle born are 25% of the wizarding population and that halfbloods and purebloods weren’t included in the cencus, that gives us
56,310 * 4 = 225,240
225,240 wizards alive in 1980. Assuming that natural wizarding life expectancy was around 100, there are
225,240 / 100 = 2252
2252 wizards/witches born/dying each year. According to the National Center for Education Statistics site I found, American Middle and High Schools together average around 1400 kids for 7 years. That’s
1400 / 7 = 200
200 kids per school per grade. Based off this, there should be
2252 / 200 = 11
11 schools for the UK if they’re all 1st to 7th year, more if some are split up in some way. Therefor, the student population of Hogwarts would be
200 * 7 = 1400
1400 students. There would be
1400 / 4 = 350
350 students per house, and
350 / 7 = 50 or 200 / 4 = 50
50 students per house, per grade. Assuming that you have one teacher for every 20 students, you would need
