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 || Neck Size |
| X-Small || 9 to 12.5 inches || 7.5 inches |
| Small || 12 to 18 inches || 9.5 inches |
| Medium || 16 to 22 inches || 12 inches |
| Large || 20 to 29 inches || 14.5 inches |