Eh, it's not something I'm too specific or even consistent about in play. I just assume 'significantly smaller than a Nord' and leave it there because I'm not very good at visualizing heights. Hence the '-ish' at the end. ;)

(Not unrelated: I had a character in days of yore who was about 5'4'' but muns tended to assume from his icons he was at least 6'. Many quiet corrections in narration ensued.)