The child is in the growing period, and the length of the foot is changing all the time, so it can't be treated according to the standard of growth. Therefore, we must take age into account when looking at the children's shoes size comparison table, so as to buy the most comfortable shoes. Generally speaking, the comparison table is mainly based on the growth law of ordinary children in scientific research, so there may be some errors between it and the actual situation, and the error is not big.