Shoe Size	Average Age	Foot Measurement
4	12 months	Up to 4.75 inches
6	18 months	up to 5.25 inches
8	24 months	up to 6 inches
10	3 years	up to 6.5 inches
12	4 years	up to 7 inches

Measure your baby's feet with socks on, from the tip of the big toe to the heel.
Measure both feet and use the larger of the two measurements, to select the size.
Toddlers tend to curl their toes when you try to measure, so make sure the feet are flat, preferably while they are standing.