I'm 13, and I was wondernig if I was old enough to move out with a friend...

No, you are too young to legally do this. Your parents can make you return to their home.

Sorry not even close, try another 5 years, you have to be 18 in most US states ( 17 in a few)

Why do you want to move and with whom ?

The older a child turns the more influence it has on the courts, but it would have to be initiated by the other parent you will be wanting to stay with. And if the other parent can state that it is in the best interest of the child, the courts may agree, but very hard to do and depends on the agreement between your parents. Lots of things are involved in that.