Feet length 24.5 cm = Size 39 Feet length 25 cm = Size 40 Feet length 25.5 cm = Size 41 Feet length 26 cm = Size 42 Feet length 26.5 cm = Size 43 Feet length 27 cm = Size 44 (1 inch=2.54cm 1cm=0.3937inch 1cm=10mm) Please tell us your feet length if you don't know which size is better for you,then we can decide your shoes size precisely. For example, if your foot length (Heel to Toe) is 25 cm,please choose size 40