Template:AgeFull

Copied from Wikipedia's Age in years, months and days template. The three parameters are "year", "month", and "day", all optional. Here's what happens if you supply a specific date:

"Oni is {{AgeFull|year=2001|month=1|day=29}} old"
yields
Oni is 23 years, 2 months, and 29 days old

whereas "Oni is {{AgeFull|year=2001|month=1}} old"
yields
Oni is 23 years and 2 or 3 months old

and "Oni is {{AgeFull|year=2001}} old"
yields
Oni is 22 or 23 years old

If you're content with just getting an age in whole years and you don't want the equivocating "X or Y years old", use the simpler template Template:Age.