How old was Stuart Little when he died?

I'm curious, could you please clarify the context for this question? Stuart Little is a character from a series of children's books and films, and as a fictional character, he doesn't actually die. Is there perhaps a specific adaptation or interpretation of the story you're referring to? I'd be happy to discuss that with you if you'd like. However, if you're asking about the character in the original books and films, it's worth noting that Stuart Little continues to live and adventure throughout the series.