When Caroll Spinney appeared at BAM last year, I believe he said that Oscar was 43. Actually, Oscar might have said that himself. There's an episode of Sesame Street I'd watched recently where Ernie explains to Bert that he has to go through preschool and all the other grades before he can go to school to become a doctor. So, I guess that would make Ernie the age where he's about to start, or in, preschool.