So, I think Aizawa’s capture weapon being about 30’ seems about right.
According to this site:
http://personal.cityu.edu.hk/~meachan/Online%20Anthropometry/Chapter2/Ch2-18.htm
The average bideltoid -forearm to forearm instead of shoulder blade to shoulder blade- shoulder breadth for a Japanese man is 44 cm, about 17 and 1/3 inches. The site also states (in introduction 1.6) that these are from military sources, so we can assume these men are decently well built. Fitting for Aizwawa, an athletic hero who stands at 183 cm (6’ tall)!
Since the width on one side of his shoulders is 17.3 inches and his capture weapon is wrapped around that width twice, as well as his actual arms, lets say a single wrap is a clean 36 inches, 3 feet.
In the (hopefully attached properly) image from the manga, there seem to be about ten wraps of this weapon around Aizawa’s shoulders, so an estimate of 30 feet seems about right.
(Though he could have more wrapped underneath the outer layers, given that we can see how thin the wraps are in this shot.)
Wow, y’all are comin at me HARD with that science! I appreciate you taking the time to reseach this, holy crap
Honestly, it’s so difficult to tell for certain! Because, judging solely by the number of visible loops on his person and estimating each loop to be around 3 feet, it definitely looks like it would be about 30 feet.
But then you get shots like these:
And it looks like the scarf has doubled in length D: Not to mention it’s been shown that Aizawa can cut lengths off of his scarf to bind enemies, and still have a generous amount left to use
Which leads me to believe 30 feet would run out pretty quickly, so it’s safer to go with a higher number. 100-200 feet would give Aizawa plenty to work with, but that’d be heavy as fUCK to carry around on his shoulders, especially something that’s metal-infused. Not to mention all the countless loops he has to keep track of when he’s fighting so he doesn’t accidentally trip himself and fall flat on his face (cause you know that definitely fucking happened while he was learning)
So I’m willing to meet in the middle and say about 60-70 feet. 30 seems quite limiting, now that I think about it, and I believe it’s a safe bet to say Aizawa has hidden layers of his scarf within itself to give himself that much more reach.
But I am definitely no scientist, and fictional weapons are not my forte lol. Who knows: maybe his scarf does magically grow and shrink to the size Aizawa needs it to be ¯\_(ツ)_/¯