How old do u have to be to sit in the front seat?

It depends on the country and state(in us). As I know it, there is no rule for cars without airbag, but for the ones with airbag it is 12. Some places it is 10. And sometimes it goes by height. Here we have a rule that says: 12 and over 1.50 cm. You should try to ask for the place you live, or ask someone in the comunity that might know.