|Baby One-Piece||0-3 (7-12 lbs)||3-6 (12-17 lbs)||6-12 (17-22 lbs)|
|Chest Width (in.)||7.5||8.25||9|
Please note that sizes are approximate, and baby one-pieces fit average to slightly small. If you are unsure, the safe decision might be to pick the next size up. Chest is measured from armpit to armpit and the length from high point collar to bottom of the One-Piece.