Are they enormous (like 6+ pounds), stinky, baldish and eating a TON of food? If so they're meaties...
If on the other hand they are still small (can they easily fit in your hand?), nearly fully feathered (maybe their heads are still downy?), and flying/hopping all around then you probably have some type of white layer or dual purpose (leghorns or plymouth rocks come to mind).
A pic would help us help you super fast!