My 22 pound one year old fit perfectly in a 2t. I"d say the 2t fits like a 18-24 month. Only thing I didn't know is that the 2T has a 2 on the back of it. Not sure if all do- or if it goes by age sizing. Didn't matter much, still looked great in the pictures. Only real critique is the aplique is almost a little too heavy....really great quality but very thick.