I think it varies a lot, since no one has been able to give me a straight answer. Temperature, food, and health are factors I guess. Generally they grow quickly until they hit 2'' and then it slows down. I've seen my 1'' frog grow very rapidly in just less than a month, now he's about 1.5.'' My 2 1/4'' on the other hand hasn't grown at all since I've had him (2 months).