I’m probably not a good source of information for this tee, but I will say it fits way bigger than I expected. (Petite adult female) I’m 5’0 about 95ish pounds, not a lot of fat, thin but slightly muscular. I ordered a small and it is super baggy on me, it would take at least two sizes smaller to be compression fit. I’m disappointed because I was worried it would be too small, it turned out being way too big.Well the shirt was of good quality but according to the ad, it says it was a boy's size and so I ordered the extra large like I always do but this in no way was a boys size because it was way too big and offered no compression at all. I'm thinking if I ordered size small it may have fit perfectly but I didn't want to take that chance and possibly have to return that one as well. I ordered another brand in a men's extra small and it fit perfectly.The sizing is way off. I got a size small for my large 8 year old. It’s basically a dress on him. It fits me and still has no compression in the arms because they are so loose. The small is more like an adult M in the abdomen and XL in the arms compression shirt.