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.
![alt text](http://cms-www.chewy.com/images/pdp-attachments/HarnessMeasuringGuide-Neck&Girth.jpg ""Chest Girth Measuring Guide"")
| Size || Neck Girth || Breast Girth |
| Small || 9.5 to 11.5 inches || 13.0 to 19.0 inches |
| Medium || 11.5 to 14.0 inches || 15.0 to 22.0 inches |
| Large || 13.0 to 16.0 inches || 19.5 to 29.5 inches |
| X-Large || 16.0 to 19.0 inches || 21.5 to 31.5 inches |