At the moment that age limit is dictated by the Children's Online Privacy Protection Act which was made Federal Law in America in 1998.
But Zuckerberg says he's willing to fight to change the law.
He says it's a battle worth taking on because of the educational benefits of using the site.
"That will be a fight we take on at some point.
"My philosophy is that for education you need to start at a really, really young age.
"Because of the [legal] restrictions we haven't even begun this learning process.
"If they're lifted then we'd start to learn what works." (read more)