What do you think of this:
Instead of just assuming that he is average adult male height, still use comparison of his Overworld sprite to Frisk one. Yes, such sprites are bit inconsistent, but both them and combat
sprite support him being pretty tall, even compared to other tall monsters. And we know that monsters can be taller than humans with ease. Kris is noted to be shortest in their party, and they are 16 year old teenager(age at which people stop their growth for the most part).
This will yields height of around 190 cm or less, which isn't out of reach by any means