When trying to decide between two sizes, choose the larger size for a better fit.

SizeSize/Age RangeChestHeightWeight
0-6 MonthsNewborn-6 months7.252.55.0 oz
6-12 Months6 Months-12 Months8.752.755.0 oz
12-18 Months12 Months-18 Months9.7535.0 oz
18-24 Months18 Months-24 Months10.753 1 /45.0 oz