What is the regulation size for a 12 and under softball bat?

I have a softball bat, but I'm not sure if it's legal to use. Anybody know what the size ranges are or atleast what the bat ratio is?|||i'm on a 12u team, and the bat size doesn't matter... as long as you can swing it and it's not too short or long, then you should be fine!|||There isn't one. As long as your bat has the ASA certified logo and says it is approved by NSA, you know it is legal.