Adidas Velcro Lightweight Soft Sole Children's Beach Sandals Size Chart Measuring your foot length is the key to size selection. Different brands and different series of shoes will have different shoe sizes. Be sure to measure your baby's foot length and compare the foot length with the size chart [Refer to Suitable Foot length] Choose the number of sizes. The child's foot length will change when he is 3 months old. Spend an extra minute choosing the size and save a week of changing sizes. Slippers and sandals