These are the flexible sizes for respective age group as per mentioned in CM

AGE	LENGTH	CHEST	SLEEVE
3-4Y	39	34	33
4-5Y	41	35	33
5-6Y	42	36	34
6-7Y	46	37	36
7-8Y	48	38	37
8-9Y	51	39	38
9-10Y	53	42	45
10-11Y	58	45	50