How to Measure a Dog for a Harness (and Check the Fit)

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Most harness problems come down to size: a harness that is too loose lets a dog back out of it, and one that is too tight rubs behind the front legs. This page shows how to measure your dog for a harness, how to choose between two sizes, how to check the fit once it arrives and the signs that a harness does not fit.

The short answer: with your dog standing, measure around the widest part of the rib cage, just behind the front legs, and around the base of the neck. Compare those numbers with the brand’s own size chart, not your dog’s weight. Once the harness is on, you should be able to slide two fingers under every strap, and no strap should rub behind the front legs.

How we wrote this: the steps come from the American Kennel Club and the harness brands’ own sizing guides, each linked where it is used. We have not tested these harnesses ourselves. Size charts differ between brands, so always check the chart for the exact harness you buy.

What you need

  • A soft measuring tape. No tape? The AKC suggests a piece of string, ribbon or a shoelace: wrap it around, mark where it overlaps, then lay it flat and measure it with a ruler.
  • Treats, to keep your dog standing still.
  • A helper, if your dog wiggles.

How to measure your dog for a harness

  1. Stand your dog up. The AKC says to measure while your dog is standing naturally, so the spine is straight and the weight is even. A sitting or lying dog gives a wrong chest number.
  2. Measure the chest girth. Wrap the tape around the largest part of the rib cage, usually just behind the front legs. This is the most important number for most harnesses. 2 Hounds Design sizes its Freedom harness from this measurement alone.
  3. Measure the neck girth. Measure around the base of the neck where a collar sits. The AKC says to start near the withers, the ridge between the shoulder blades, and bring the tape around to the front of the chest. Many harnesses have a neck strap, so this number matters too.
  4. Keep the tape snug, not tight. The AKC suggests slipping two fingers between the tape and your dog when you measure around the body.
  5. Write both numbers down and compare them with the size chart for the harness you want.

Weight or measurements?

Many size charts list a weight range, but two dogs of the same weight can have very different chests. A deep-chested sighthound and a stocky bulldog type of the same weight need different sizes. Use the chest girth first and weight only as a tiebreaker. That is how 2 Hounds Design sizes its harness: by chest measurement, with a weight range only to choose between two strap widths.

Between two sizes?

There is no single rule, so follow the brand. The AKC says that for clothes and gear, the larger size is generally the safer pick because a slightly looser fit is more comfortable. For its harness, 2 Hounds Design says the opposite: choose the smallest size that still fits, because a harness that is too big fits badly across the front. Check whether the harness you want has adjustable straps at the neck and the chest. If it does, you can tighten a larger size, but a strap that is already at its tightest has no room left.

How to check the fit

  • The two-finger check. The AKC says you should be able to fit two fingers under the straps, with your dog both standing and sitting. 2 Hounds Design puts it as two fingers, but only two.
  • Nothing rubs behind the front legs. Blue-9 says straps should not dig into or rub behind the front legs. The AKC adds that the girth strap should sit behind the rib cage, not squeeze into the backs of the elbows.
  • The shoulders move freely. Watch your dog walk and trot. The AKC lists restricted shoulder movement and a shortened front-leg stride as signs of a poor fit.
  • The front clip sits on the chest, not low on the stomach or up near the throat, on a front-clip harness.
  • Try to back it off. With the leash on, gently pull forward from the front. If the harness slides over your dog’s head, tighten the straps. The AKC notes that dogs can more easily slip out of a poorly fitted harness.

Signs a harness does not fit

  • Rubbed fur, red skin or sores behind the front legs or on the chest. The AKC mentions fur and skin rubbed raw by badly fitted harnesses.
  • Your dog walks stiffly, shortens its stride or refuses to move in the harness.
  • The harness twists to one side during walks.
  • Your dog wriggles out of it.
  • You cannot fit two fingers under a strap, or you can fit your whole hand.

It is a good habit to check the fit again every few weeks for a growing puppy, after a change in weight and when your dog’s coat grows out or is clipped, since all of these change the measurements.

Harnesses in our catalog

Check each brand’s own size chart before you order:

For a dog that pulls, our best dog harness for pulling page compares these in detail, and the leash, harness and carrier buying guide covers collars, leashes and car safety.

FAQ

Where do you measure a dog for a harness?

Around the widest part of the rib cage, just behind the front legs, and around the base of the neck, with your dog standing. Compare the numbers with the size chart for the harness you want.

Should a dog harness be tight or loose?

Snug but not tight. You should be able to slide two fingers under each strap, and no more. Too loose and your dog can back out of it; too tight and it rubs.

Should I size up or down if my dog is between harness sizes?

Follow the brand’s advice. The AKC says the larger size is usually more comfortable for gear in general, while 2 Hounds Design says to choose the smaller size for its harness. Adjustable straps give you room either way.

Can I use my dog’s weight to choose a harness size?

Only as a rough guide. Chest girth is more reliable, because dogs of the same weight can have very different builds.

How do I know if a harness is rubbing?

Look for thinning fur, redness or sores behind the front legs and across the chest after walks. Adjust the straps or try a different style if you see them.

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