Heyo! So I did some math for some fun (I know, doing math for fun! what am I a nerd?) and I decided to measure out how tall all of the characters in Nuclear Throne are. But to do that I needed a base comparison so I decided to pick the only "normal" person in the group and that is Rouge. Rouge is a (more or less) normal human and if that is true then I can use her to find out everyone else's height in game. Now according to this website: https://www.cdc.gov/nchs/fastats/body-measurements.htm the average (American) women's height who are over 20 is about 63.8 inches. (now I know that I am assuming things like where she was born and how old she is but still, this is just for fun) Now if I take that height and spread it out to each of her pixels, it would make each pixel about 2.63 cm (or .93 inches). Now in this picture you can see the height of each character in CM, Inches, and Feet & Inches.
Now before you guys say I missed Plant, I need you too see that Plant's feet are not fully linear with the ground so measuring it's height would be really hard with it being a 3D view vs how the other sprites are at a 2D view.
Also keep in mind I'm not claiming this is 100% true, but in terms of size scaling with the In-Game-Sprites that's what I got.