How old is an Animal Crossing character

that's actually quite a good question to be honest. Your personal character is as old/young as you want them to be (normally ages 10-15) but the citizens of most towns can have varied ages for instance, Caroline the squirrel (red and yellow pelt) is known to be quite young so about 16 or 17 whereas Curt, the moody gray bear is getting on a bit at the age of about 25 to 30. These are some other town folks who have ages:

Tom Nook: 20-30
Sable: 20-30
Mable: 20-25
Pelly: 25
Phyllis: 30
Rooster: 40
Blathers: 35
Pete: 25

hope you find this useful :)