AB's can vary greatly in size, and there really is no average. It depends on your pups genetics..what were the size of his parents..what bloodlines does he come from? I have seen some AB's that were close to 30" tall and weighed 130+ pounds, while I have seen others that were 20" tall and 60 pounds (if that). The breed isn't your cookie cutter type breed, so really, you need to look to your dog's breeder for a better understanding of your pup's maturity levels.