To get the most accurate size harness for your pet, measure the girth of their chest, around the widest part of your dog's torso right behind the front legs, with a cloth tape measure. Pull the cloth tape snug, but not tight. If you don't have a cloth tape measure, you can use a piece of string and measure it with a rigid ruler afterwards. Make sure there's enough room for about two fingers between the harness and your pet's chest for comfort.
| Size || Chest Girth || Recommended Pet Weight |
| X-Small || 16 to 22 inches || 15 to 25 pounds |
| Small || 21 to 27 inches || 20 to 30 pounds |
| Medium || 26 to 32 inches || 25 to 50 pounds |
| Large || 29 to 43 inches || 65 to 80 pounds |