My 5 year old is about 42 inches tall, weighs 39 pounds and wears size 44 shoes. I ordered 9C-1Y and they fit perfectly! might wear them for a few more years (if he doesn't destroy them), but not so big that the heel is over the back of the boot. Posts for the protection of a shin. When he puts them on fully, they reach his knees. I definitely want to buy more in other colors!