First, these are ADULT size socks.  There are similar socks in child size.  The child size were a bit small for my 12 yr old grandson (size 5 shoe), so I got him a pair of these.

The sizing is standard adult size - a little large in foot for a size 5 shoe, and almost to knee on the leg of a small 12 yr old, which I expected.  These would easily fit his (510) Dad as crew socks.

Grandson loves them and wears them as soon as they are out of the wash.  Hed only wear these socks if possible!  Will probably need to get more!

These are thin socks, made for their novelty more than quality.  They are not going to wear or last like average quality socks.  You are purchasing fun, not standard wearability.  And fun they are.