Its says on the under armour website that its supposed to fit a child size of 7-8 but I wore this 3 years ago when I was 14 and my height was 5-9 and it fit perfect. It hasn't been wore too much either, I had only wore it when it came to hunting and ice fishing season. Also remember that it is a thermal shirt that is supposed to be a little tight and is usually used for cooler weather days.