Supposedly, during the signing at SDCC, Bryke said they were confused about all the people thinking Korra is short. They said she’s “about 5'7” “ and that "Mako is about 6'2” “. And since we also know P'li is 6'8”, a more accurate (though not definitive by any means) height chart can be made.
Personally, while this sets Korra up as being a little above average for height in the Real World, she still ends up being on the short side of average for the Avatar Universe because pretty much everyone else is that much taller.
I still think it looks more sensible to have Korra at 5'3" because that makes P'Li’s awesome towering height that much more towering to everyone in comparison.
Note: This chart assumes that the “old friends” and “new friends” posters are made to scale with each other.
This is what you do to your fandom. You make us believe in worlds where people can control the elements with kung fu, where spirits are tangible and beautiful, where there is legitimately no limit to what anyone can do regardless of disability, gender, or race…
and then break us with the weirdest heights that are so hard for many of us to find rational. Like the entire Gaang growing two feet from their confirmed heights in AtLA. OMG ZUKO HAD THE HUGEST GROWTH SPURT BETWEEN 17 and 20.