I forgot to add, in the movies, I think the characters are meant to be pretty close in age to the ages of the actors. So that would have made them (based on actors' ages in 1983, when the movie was being shot): Ray, 32 years old, Peter, 33 years old, Winston, 38 years old, and Egon, 39 years old. Give or take a couple of years, I mean, Ramis has never looked his age, usually looked younger, so you could slash a couple of years off Egon... same for Hudson as Winston, for that matter. IDW seems to have aged Peter a bit, since he's the only one with visible grey in his hair, in the comic.