Thanks for the excellent resource link, Kitty!
Now, to critique that resource:
I did a few quick checks for relatives to test the accuracy and found the computations to be a day or two off [the 2-day error was for my aunt, a leap-day baby (NOT born Feb. 31)!]
Note that I consider someone who died on his/her birthday to be x-years, 0-months, 1-day old. Other systems may not count that day.
Still, that's close enough, considering that the data for age at death could be inaccurate or incomplete anyway!!