When trying to decide between two sizes, choose the larger size for a better fit.
| Size | Size/Age Range | Chest | Height | Weight |
| 0-6 Months | Newborn-6 months | 7.5 | 17-24 ins | 11-14 pounds |
| 6-12 Months | 6 Months-12 Months | 9 | 25-27 ins | 15-20 pounds |
| 12-18 Months | 12 Months-18 Months | 10 | 27-30 ins | 21-24 pounds |
| 18-24 Months | 18 Months-24 Months | 11 | 30-33 ins | 25-29 pounds |
| One Size | ||||
| 2T | 2 Years | 12 | 33-35 | 28-30 pounds |
| 3T | 3 Years | 13 | 36-38 | 30-33 pounds |
| 4T | 4 Years | 14 | 39-41 | 34-39 pounds |