SO! I was interested in the official height of the characters in ATLA after reading an older forum on the topic here . After poking around the internet, the closest thing to an "official" height that I found was a character height comparison chart in Nick's How to Draw AVATAR. (you can see the pages here and here if you'd like)
From there I employed a little SCIENCE! Well, more math, but anywho. I found the pixel height of each (human) character and from there extrapolated their "official" heights!
Aang ––– 4’ 6” = 137.16 cm
Katara –– 4’ 9” = 144.52 cm
Toph ––– 3’ 8.5”* = 113 cm*
Sokka –– 4’ 11” = 150.3 cm
Zuko –––- 5’ 1/2” = 153.45 cm
Azula ––– 4' 3.7"^ / 4' 7.86"* = 131.38 cm^ / 141.89 cm*
Iro ––––– 4’ 9.5”^ = 146.09 cm^
Jet ––––- 4’ 10” = 148.2
Roku ––– 5’ 6”^ = 167.11 cm^
* with hair/topknot
^ without topknot
Now if you haven’t noticed, there all pretty short. Roku, who’s supposed to be all tall, stands at my height. To put in perspective, that’s the average height for women in the U.S. I got these heights off the premise that Aang is 4 ft. 6 in. found in a comment in the previous forum claiming it as “official.” (whether or not it’s true, I dunno)
Azula’s lack of height may also be in part to the fact that in the height chart she’s partly crouching. In my final calculation for pixel height, I used some photo manipulation magic to properly align her plumline to try and get a truer height.
I tried to better find out how true these small heights were by extrapolating adult height from them. The best matching age progression height charts were from an adoption site for Chinese nationality, here . Even those didn't fit for Toph, who's estimated adult height would be 4ft. 3 in. or 130 cm.
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But here's where you all come in. I made an Excel spread sheet (oh yeah, I went there) to calculate their heights based on the premise of Aang’s height. It allows for someone to change their guess for Aang’s height (in inches, sorry rest of the world, the conversion rate is 2.54) and get relative heights based on the static pixel height ratios.
If you want my Excel spread sheet you can download the .xlsx here and the .xls here . If you have a guess at Aang's height or any suggestions, please comment! IN FACT PLEASE COMMENT IN GENERAL!