do not look at the weight range when decide on a size . my son be at the top end of the size large weight range , but this item will still fit he for many month . instead , look at the height range for a more accurate size determination . my tall son be grow out of size 18-24 month clothing , but the size large sleepsack -lrb- size 12-18 month -rrb- will fit he for many more month .