We bought size L for our 12 year-old son. It is huge. The packaging says it is for a 14-16 year old. The 12 year-old is disappointed and our 15 year-old who can never get clothes (too small for mens' and too big for boys ranges) is delighted. I am ordering a size medium for our 12 year old and maybe another large in a different colour for our 15 year-old. Shame the small will probably be too big for our 8 year-old.