A harness that fits well is comfortable, hard to back out of and gives you steering when your dog pulls. One that fits badly rubs, twists to one side or slips off at the worst moment, like next to a busy road. Here is how to measure before you buy and check the fit once it arrives.

Before you buy: measure

  • Chest girth: wrap a soft tape measure around the widest part of the rib cage, just behind the front legs. This is the number most size charts use.
  • Neck: measure around the base of the neck, where a harness strap would sit, not high up where a collar sits.
  • Weight: some charts use it too, but trust the chest measurement first.
  • Use the chart for that exact harness. A medium in one brand can be a large in another.

The 6 point fit check

  1. Two fingers under every strap. You should be able to slide two flat fingers under each strap. If you can fit your whole hand, it is too loose. If you cannot fit two fingers, it is too tight.
  2. Armpits clear. The strap behind the front legs should sit about a hand's width behind the elbow, not right in the armpit where it can rub.
  3. Chest ring centered. On a front clip harness, the leash ring should sit in the middle of the chest, on the breastbone. If it slides off to one side when you walk, tighten the straps evenly.
  4. Shoulders free. Watch your dog walk and trot. The straps should not press across the front of the shoulders or stop the front legs from reaching forward. If they do, try a harness with a Y shaped front.
  5. Escape test. Gently pull the harness forward, toward the head, the way a dog backing away would. It should not slide over the ears. Do this at home, not on your first walk.
  6. Check again after a week. Straps loosen with use, coats change, and puppies grow fast. Re-check the fit every week for growing dogs.

Make the harness something your dog likes

  • Show the harness, then give a treat. Repeat a few times before you put it on.
  • Hold the neck loop open and let your dog push its head through for a treat on the other side.
  • Buckle it, treat, and take it off again. Build up to a few minutes around the house before the first walk.
  • If your dog ducks away from things going over its head, pick a harness with a neck buckle.

Signs the fit is wrong

  • Red skin, hair loss or a sore spot under a strap. Adjust the fit or change the style, and ask your vet if the skin looks irritated.
  • Your dog walks oddly, freezes or scratches at the harness well after the first few tries.
  • The harness spins around so the chest ring ends up on the side.
  • Your dog can wriggle out of it when it pulls back.

Next steps

Still choosing? Our comparison of the best no pull harnesses explains the main styles and who each one suits. Once it fits, start the step by step loose leash walking guide, or grab the free PDF, The 7-Day Calm Dog Plan, for simple daily steps.

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