Please choose according to the length of your baby's feet (measured on the ground) plus 0.8- 1.3cm or according to the normal size plus one size or measure the insole. the length of the insole = the inner length of the shoe

The inner length of size 21 is 13.5cm, the inner length of size 22 is 14cm, the inner length of size 23 is 14.5cm, and the inner length of size 24 is 15cm. 

The inner length of size 25 is 15.5cm, the inner length of size 26 is 16.3cm, the inner length of size 27 is 17cm, and the inner length of size 28 is 17.5cm.

The inner length of size 29 is 18cm, the inner length of size 30 is 18.5cm, the inner length of size 31 is 19.2cm, and the inner length of size 32 is 19.8cm 

The inner length of size 33 is 20.3cm, the inner length of size 34 is 20.8cm, the inner length of size 35 is 21.4cm, the inner length of size 36 is 22cm