I am well aware that scale does not exist in this franchise, and that my research was cursory at best, so take all of the following with a grain of salt.
So, the Dinobots. In terms of alt modes, we have:
Grimlock: Tyrannosaurus rex (40 feet long, 13 feet tall at the hips, 14 metric tons)
Snarl: Stegosaurus stenops (30 feet long, about 3 tons)
Slag: Triceratops horridus (26-30 feet long, 6.1-12.0 metric tons)
Sludge: Brontosaurus excelsus (72 feet long; 15 tons).
Swoop: Pteranadon longiceps (6 feet tall, 20-23 foot maximum wingspan, possibly around 35 pounds)
With the exception of Swoop, who’s roughly human-sized in alt mode, discounting the wings, they’re all pretty large, but not exceptionally so, especially compared to the alternate modes of most Decepticons. (Brawl, a Leopard A1 main battle tank, is 31 feet long; Vortex, a Kaman SH-2 Seasprite, is 44 feet long; the Seekers, who are all F-15 Eagles, are about 64 feet long, etc.)
This gave me the idea of scaling the Dinobots’ alternate modes so that they’re the same size proportionately to an Autobot car (usually around 13-15 feet tall) that the dinosaur off of which their alternate mode is based would be to a human. While this is absolutely not necessary for the fiction (especially since, as noted above, scale does not exist in this franchise), I thought it would be interesting to see the results. Assuming that we’re measuring dinosaurs against a six-foot human male, this means that we’re working with a size increase of (very roughly) X 2.5, which gives us the following results:
Grimlock: 100 feet long, 32.5 feet tall at the hips (note that Grimlock would probably be considerably taller at the head since he’s an anatomically inaccurate Tyrannosaurus who stands upright), approximately 35 metric tons.
Snarl: 75 feet long, approximately 15 tons.
Slag: 65-75 feet long, approximately 15.25-30 metric tons.
Sludge: 180 feet long, 37.5 tons.
Swoop: 15 feet tall/long, 50 foot wingspan. He’d definitely be more than 87.5 pounds, since he’s made of metal and doesn’t need to be lightweight in order to fly like a real Pteranadon would, but that is what a 2.5 increase in weight would be compared to the original weight.
So if you want your Dinobots to be really big…there you go. (Well, except Swoop. Even X 2.5 his dimensions are only about equal to those of the Autobot cars…though he does have a longer wingspan than the F-16, the F-4, the Harrier II Jump Jet, and even the F-15).
Other useless (but funny) scale information:
Groove, the Honda Goldwing GL 1200 Police Motorcycle, is only about eight feet long. If we’re nice to him and multiply his stats by 2.5 like we did with the Dinobots, that increases to 20 feet and actually makes him a bit larger than his generally 13-15 foot long car teammates. His weight would also increase from 875.5 pounds to 2,188.75 pounds. This would, however, make his motorcycle mode completely worthless as a disguise. (The Dinobots don’t have this problem. Since they transform into metal versions of extinct animals, they’re not fooling anyone regardless of how close they are to the size of the actual animals.)
Blades, his teammate, is a Bell UH-1V Iroquois Helicopter, and as such, is about 57 feet long and weights about 5,125 pounds (I’m presuming this is empty). If we decrease his size in the same way that we increased Groove’s, this would make him 22.8 feet long and 2,050 pounds. He’d still be a little big, but he’s scale much better with his teammates than he would at full size.
Streetwise is pretty simple. He’s a Nissan 300ZX Turbo police car. He’s 14.2 feet long and weighs in at 2,888-3,280 pounds, so pretty standard for a car.
First Aid is a Datsun Vanette C120 ambulance, and he’s….surprisingly short. A Datsun Vanette C120 is only about 14 feet long. He’s also about five and half feet wide, and weighs in at a surprisingly light 1,907-2,315 pounds. Have I been overestimating ambulance size this whole time, or is he just at tiny ambulance? Note that Ratchet and Ironhide are very similar in size to First Aid, as they are also Datsun Vanettes.
Hot Spot is a Mitsubishi Fuso Great Fire Engine, which was surprisingly difficult to find stats for. Based on the information I could find, he’s nearly 25 feet long (24.93 feet) and weighs in at 16,931.5 pounds, making him the heaviest member of the team even if Blades is at full size. So, if we increase Groove’s size by X 2 (X 2.5 seems a bit large) and decrease Blades by the same amount as we originally increased Groove, we’d actually have a kind-of sort-of reasonably scaled Protectobot team! As it stands, though, Groove and Blades are throwing everything off to a hilarious extent.
The Combaticons are a nightmarish mess. Since Swindle has become very strongly tied to a jeep alternate mode even though his original toy did not transform into a jeep, and his alternate mode animation model looks a LOT like Hound’s, I’ll be working off the assumption that Swindle is, in fact, a J59 Jeep, just like Hound. This would make him about 11.5 feet long and 2,665 pounds. This is small. If we multiply these stats by 2.5, this gets us 28.75 feet and 6,662.5 pounds. This would be a huge jeep, but he’d still be smaller (or at the very least, lighter) than all of his teammates.
Brawl is a Leopard A1 Main Battle Tank. (His animation model doesn’t LOOK like one, but neither is it incredibly obviously something else, as is the case with Swindle.) Counting the fully extended turret, he’s 9.54 meters, or 31.3 feet, long. (The main body of the tank is somewhere around 27 feet long.) He weighs in at 46.5 tons (that’s 93,000 pounds!) However, as far as length is concerned, he scales reasonably well with a x2.5 Swindle.
Vortex is a Kaman SH-2 Seasprite helicopter. He’s 38 feet, 4 inches long and weighs 7,040 pounds empty. This means he’s about 7 feet longer than Brawl (including the turret), and about 10 feet longer than Swindle x2.5. Even at his absolute maximum weight capacity (13,300 pounds) he’s still FAR lighter than the tank, however.
Onslaught is a headache, because, while he’s obviously an anti-aircraft truck, neither his toy nor his animation model appear to be any particular type of anti-aircraft truck, making it really difficult to guess as to how large he might be.
A YouTube video posted by a user by the name of Nemesis Bloodryche suggests that he looks similar to the Russian BAZ-6909 10x10. It is 11,300 millimetres, or about 37 feet, long, and weighs 48,502 pounds (or about 24 tons). This would scale appropriately with Brawl and reasonably well with Vortex.
Blast Off is a space shuttle orbiter. (If he was the full space shuttle, he’d be even more massive than this!) He’s 122 feet long, with a width of 58 feet and 7 inches and a wingspan of 78 feet. This means that he is wider than any of his teammates are long. He weighs in at a 53,930 pounds, which, while impressive, is somehow still less than Brawl (93,000 pounds). He’s 3 times longer than Vortex and Onslaught, 4 times longer than Brawl sans turret and Swindle X 2.5, and almost 11 times longer than a properly-scaled J59 Jeep Swindle. Needless to say, he and Swindle are the main reason that Bruticus is such a mess, scale-wise. Believe it or not, though, Blast Off still isn’t the worst in terms of scale. Also, if we kept Swindle’s increased size and decreased Blast Off’s size by the same factor, things would at least become slightly more reasonable, as this would give us a 48.8 foot long Blast Off, which, while still big, is not as ridiculously so.
Most of the Aerialbots, being fighter jets, are at least somewhat reasonably scaled. Slingshot, the Harrier II, is 46 feet long and 12,500 pound empty; Skydive, the F-16, is 49 feet, 5 inches long and 18,900 pounds empty; Fireflight, the F-4 Phantom II, is 63 feet long and 30,328 pounds empty; Air Raid, the F-15 is nearly 64 feet long and weighs 28,500 pounds empty. It’s not perfect by a long shot, but it works if you squint, especially since Slingshot is usually depicted as smaller than the others. And then Silverbolt ruins everything. Silverbolt is a Concorde SST, 202 feet long and 173,504 pounds empty. He’s longer and heavier than Blast Off, the space shuttle orbiter! Sure, the torso should logically be a bit larger than the combiner limbs, but this is just ridiculous. He’s 3.2 times longer than Air Raid, his longest teammate, and 5.7 times heavier than Fireflight, his heaviest teammate! He’s even 1.86 times heavier than the 46-ton tank and 1.65 times the length of the space shuttle orbiter! If we reduce his size by a factor of 2.5, Silverbolt would be 80.8 feet long and weigh 69,401.6, which, while not perfect, would be a lot more manageable than a full-sized Concorde SST.
The Stunticons have a similar problem. The four small cars actually scale even better than the Aerialbots. Drag Strip, the Tyrell P34, is 13.58 feet long and weighs 1,370 pounds. Breakdown, the Lamborghini Countach, is also 13.58 feet long, and weighs 2,978 pounds. Wildrider, the Ferrari 308 GTB, is 13.87 feet long and weighs 2,784 pounds. And Dead End, the Porsche 928, is 14.8 feet long and weighs between 1,450 and 1,620 pounds. They’re not perfect, but they’re all within less than three feet of one another! That’s considerably better than the differences between the smaller Aerialbots, and MUCH better than the scale difference between, say, Blades and Groove. But then there's Motormaster. He is a truck and trailer. The “truck” part is the Kenworth K100 Aerodyne sleeper truck, which is about 20 feet long. The problems come in with the “trailer” part. A box trailer is about 48 feet long, and, since Motormaster’s robot mode is composed of both truck and trailer, this makes him around 68 feet long, with a rough weight estimate of somewhere between 10,000 and 25,000 pounds. While he’s not as huge as Silverbolt, he is just as large, if not larger, compared to his largest teammates, being 4.6 times longer than Dead End and 3.35-8.37 times heavier than Breakdown. Again, thanks to the YouTube video mentioned above for the length of the trailer. That being said, if we did what we did with Blades and Silverbolt and reduced his size by a factor of 2.5, Motormaster would be 27.2 feet long and between 4,000 and 10,000 pounds, and things would actually scale rather well. (This would also help to mitigate the scale discrepancy between Motormaster and Optimus Prime.)
Astrotrain, like Blast Off, is a space shuttle orbiter, 122 feet long and 53,930 pounds. However, unlike Blast Off, he is also a train: the JNR Class D51, which is 64 feet long. (There is a weight listed for the train, 76.8 tons, but I’m not sure if this weight refers only to the engine. Astrotrain’s body is composed only of the engine, not the entire train.) This means that, when transforming from a train into a space shuttle, Astrotrain almost doubles in length!
Broadside transforms into some sort of fighter jet (neither the G1 toy nor the animation model resemble any known jet enough to tell for sure). For the sake of argument, we’ll say he’s an F-15. The F-15 is almost 64 feet long. His other alternate mode is an aircraft carrier. A Nimitz class aircraft carrier is 1,092 feet long. Broadside’s aircraft carrier alternate mode would be 16 times longer than his airplane mode! Even Silverbolt, who is massive, would be 5.4 times shorter than Broadside’s aircraft carrier mode! As insane as Astrotrain’s doubling in length is, Broadside increasing his size by a factor of 16 is much, much more so.
Metroplex transforms into….a city? (Okay, so he really looks like he transforms into a fort, but it’s more fun to imagine the scale of a true city-sized robot.) The largest city by land mass in the US, Oklahoma City, is 621 miles squared. While square miles can’t really be used to measure distance, it is very, very roughly 16-ish miles in diameter. If Metroplex is the size of Oklahoma City (unlikely), this would make him around 84,480 feet tall. Mt. Everest is 29,032 feet tall. Metroplex would be nearly 3 times the height of Mt. Everest!
When it comes to determining Unicron’s scale, the answer depends on whether we go with the roughly moon-sized Cybertron seen in the cartoon or the apparently Saturn-sized Cybertron of the comics. Please note that these estimates are VERY rough.
The diameter of the Moon is 2,158.8 miles. If we assume, as seems probable, that Unicron at least doubles in length when he transforms, this would make him at least 4,317.6 miles tall. That’s 22,796,928 feet tall! His gravitational force would be about 1.6 meters per second squared, and would have a mass of 7.342×10 to the 22nd power kg. (Mathematical expressions don’t seem to work properly on this site.)
If Unicron is instead the size of Saturn, he would have a diameter of 72,376 miles. If we double this, we get 144,752 miles tall or 373,460,160 feet! He would have a mass of at least 5.683 X 10 to the 26th power kilograms, and a gravitational force of at least 10.44 meters/second squared. I’m also pretty sure that it would be next to impossible to get a solid planet at this size. Saturn, unlike Unicron, is made of gas, enabling it to be much larger than a metal planet could logically grow.
