Stewie Griffin is forever youthful, but his specific age remains a mystery. It's unknown the exact number
of years Stewie entered existing. The toddler persona from the animated television show "Family Guy" is forever young. His number of years is yet discovered.
Stewie Griffin, the clever little troublemaker, is hiding his true age from the world. Speculation runs rampant as to the length of time he has existed. Is he over a hundred years old? Or is he fresh to the world? The truth lies only with Stewie! This enchanting character continues to intrigue fans with his undisclosed age and forever young facade.
Les Griffin Wikipédia