Regarding the selection of children's shoe sizes, please note the following: Most children's shoe sizes are based on manufacturer's standards and do not have a unified standard (different shoes of the same size may have different dimensions). Please measure the foot length. For summer models, it is recommended that foot length + 0.5cm = shoe inner length. For spring/autumn and winter models, it is recommended that foot length + 1cm = shoe inner length (the cm indicated after each size is the shoe's inner length) Size 21 inner length 13cm cm, size 22 inner length 13.5cm cm, size 23 inner length 14cm cm, size 24 inner length 14.5cm cm, size 25 inner length 15cm cm, size 26 inner length 16cm cm, size 27 inner length 16.5cm cm, size 28 inner length 17cm cm, size 29 inner length 17.5cm cm, size 30 inner length 18 cm 1