NOTE: For the best chance of a correct fit, please measure your foot: 1) Place a piece of paper on the floor, against a wall; 2) Step on the paper, your heel against the wall; 3) Mark the paper in line with your longest toe; 4) Measure that length with a ruler; 5) Compare that length to the sizing chart.
The size your need=length of your feet+0.5~1cm.
SIZES UPDATED with 8/10/2018 SIZE CHART: 3M US Big Kid (Inner Length = 22.2cm) 4M US Big Kid (Inner Length =22.8cm) 5M US Big Kid (Inner Length = 23.5cm) 6M US Big Kid (Inner Length= 24.1cm) 7M US Big Kid (Inner Length = 24.8cm) 8M US Big Kid(Inner Length = 25.5cm) 9M Big child (Inner Length = 26.2cm)