Male GSD - Small boy, Big heart!

He is currently 22.5 lbs at 84 days(nearly 3 months). He was from a large litter (10 pups), but is growing at a good rate, he was 13 lbs when we got him at 8 weeks and he has grown about 2.5 lbs a week on average. He's not a big eater, he would much rather play or do one of his many tricks for treats (He already knows 8 commands perfectly!)

Are the growth charts at 2 months equal to 8 weeks or 60 days? I know its only a few days difference, but I'm just curious.