Approx. chest measurements for the sizes:
2 (25 inch chest circumference)
3/4 (26.5 inch chest circumference)
5/7 (28 inch chest circumference)
8/10 (29.5 inch chest circumference)
11/13 (31 inch chest circumference)
14/16 (32.5 inch chest circumference)
S/M (34-38 inch chest circumference)
L/XL (40-46 inch chest circumference)
Designed with a positive ease of approx. 5-7 inches {or more depending}.
Pictured in size 5/7 on a 5.5 year old child.