New Born : 0 months : size 44

Up to one Month : 0-1 month : size 50

Up to two Months : 1-2 month : size 56

Up to four Months : 2-4 months : size 62 

Up to 6 Months : 4-6 months : size 68

Up to 9  Months : 6- 9 months : size 74

Up to 12  Months : 9-12 months : size 80

Up to 18 Months : 12-18 months : size 86

Up to 2 years   :18-24 months : 92

Up to 3 years : 24 -36 months : 98

Up to 4 years - 3-4 years : 104

Up to 5 years : 4-5 years :110

Up to 6 years : 5-6 years :116

Up to 7 years : 6-7 years :122

Up to 8 years : 7-8 years 128

Hat Sizes 

0-6 months : 40/42 

6-24 months : 44/46 

2-4 years : 48/50