Thomas Jefferson's height was six feet two-and-a half inches tall as described by his grandson Thomas Jefferson Randolph. We often overstate the contrast between the average height today and in Jefferson's time. According to Sokoloff and Villaflor, American recruits around 1779 reached an average final hight of 68.1 inches or 5' 8 1/10" At 74.5 inches or 6' 2 1/2", Jefferson would be a good bit over six inches taller than the average male of the day--and not insignificantly tall by modern standards. Jefferson was not taller than his contemporaries because they were short, but because he was fairly tall.
Sokoloff and Villaflor put the final average height of today at between 69 and 70 inches--that is a bit over one inch taller than in Jefferson's time. From these figures it can be seen that men today are not on average that much taller than Jefferson's peers. From these figures, as well, we can derive a sense of how Jefferson may have looked to his contemporaries.
First, on average today's final height is 69.5 (based on Sokoloff and Villaflor). The following equation compares the proportion between average height in Jefferson's time and Jefferson's height with the proportion between average height today and X (with X being how tall someone would have to be now to seem to us as tall as Jefferson did to his peers):
In this proportion, X=76.032" or just a bit over 6' 4". So Jefferson would have seemed about as tall to his peers as an individual 6' 4" seems to us today.
↑ Kenneth L. Sokoloff and Georgia C. Villaflor, "The Early Achievement of Modern Stature in America" Social Science History 6 (1982):477.