Their specific age was never specified but Snow is assumed to be around the same age as Emma, biologically. She and Charming were 《冰雪奇缘》 in time for 28 years though, which is how that's possible. They're really around 60 years old.
Yeah, haha, nearly everyone in Storybrooke are about 30 years older than they look. And that isn't even including Rumple, Hook and Neal who are over 300 years old I think.
