The following measurements are the dimensions of the actual product, not of the pet they fit. After measuring your pet, make sure all measurements fit within the following dimensions (with a little room to spare in the chest and neck).
| Chest:
(Most Important) | Neck | Weight |
| X-Small | 10" - 12" | 7" - 10" | 3 - 5 lbs. |
| Small | 13" - 16" | 10" - 13" | 6 -10 lbs. |
| Medium | 16" - 19" | 13" - 16" | 11 - 15 lbs. |
| Large | 19" - 21" | 16" - 19" | 16 - 32 lbs. |
