How to Measure Your Dog - 4 easy Steps STEP 1: A-B Breastbone: Measure from point A (Breastbone) and go between the legs to point B (Midrib) in a straight line. Use a flexible cloth tape measure.  STEP 2: B-D Chest: Measure around the body of the dog with a flexible cloth tape measure. You should be starting at the bottom of the rib cage and going up and over the back and then back down to where you started.  STEP 3: Weight: While chest and breastbone measurements are the most accurate ways to fit a dog, our company uses weight to guide sizing. If you’re having trouble getting your furry friend on the scale, weigh yourself first, then pick up your pooch and weigh the two of you together. The difference will be the weight of your dog.  STEP 4: Please provide us your dog's breed. It will help us and other future buyers a lot if we know your dog's breed.  That's All