Bought a 3T for my 3.5 year old. He is 37 inches tall and weighs 35 pounds. He wears 4T in most shirts, 3T/4T in shorts, and 3T in pants (4T is too long). 3T are so big I tried them on my 5.5 year old and they fit him better. My 5 year old is 43 inches tall and weighs about 43 pounds. The quality is good and I really like the drawing, so I'm keeping it. Last season we had a well worn RB swimsuit that has been washed a million times and has kept its color well.