Measured by weight
Size chart
#0 Chest 10 inches, suitable for weight 0.5-1 kilogram.
#1 Chest 12 inches, suitable for weight 1 -1.9 kg.
#2 Chest 14 inches, suitable for weight 2 - 2.9 kg.
#3 Chest 16 inches, suitable for weight 3 - 4 kg.
#4 Chest 18 inches, suitable for weight 4 - 5 kg.
#5 Chest 20 inches, suitable for weight 5 - 6 kg.
#6 Chest 22 inches, suitable for weight 7 -8 kg.
#7 Chest 24 inches, suitable for weight 9 -14 kg.
#8 Chest 26 inches, suitable for weight 15 - 19 kg.
#9 Chest 28 inches, suitable for weight 20 - 25 kg.
#10 Chest 30 inches, suitable for weight 25-30 kg.