Size Chart Size 3-6 Months : Legnth= 37cm Chest= 23cm *2 Size 6-9 Months : Legnth= 40cm Chest= 24cm *2 Size 9-12 Months : Legnth= 43cm Chest= 25cm *2 Size 12-18 Months : Legnth= 46cm Chest= 26cm *2 Size 18-24 Months : Legnth= 49cm Chest= 27cm *2 Measured by hand, Please allow 1-3cm error