Please measure your kid's feet length, Inner Length= feet length+0.23 inches, and refer to our size chart. e.g.Your kids feet length is 5.95 inches,5.95+0.23=6.18,less than the inner length 6.3 inches,so the size 8 will fits her.If your kid's feet length +0.23 inches=inner length, then choose one size bigger.
