Model is wearing a 12-18 mo.
Measurements
0-3M width: 9 ½”, length: 15”
3-6M width: 10”, length: 16”
6-12M width: 10 ½”, length: 17”
12-18M width: 11”, length: 18”
18-24M width: 11 ½”, length: 19”
Width measurements indicate the chest width from side to side. Length measurements indicate the length from high point shoulder to snaps.