How to measure a dog for a harness

Measure the chest girth

Chest girth is the measurement every harness brand sizes by. Ruffwear, Kurgo and the AKC all measure it around the widest part of the rib cage, which on most dogs is just behind the front legs.

1. 1
   Stand your dog on all four feetThe AKC advises measuring a standing dog, so the spine is straight and the weight is even. A sitting or lying dog gives a different number.
2. 2
   Find the widest part of the ribsSlide your hand back from the front legs along the ribs. Kurgo says to measure around the widest part, starting from the bottom of the rib cage rather than tight behind the armpits.
3. 3
   Wrap a soft tape around the chestKeep it level all the way around, snug and flat against the body. On a fluffy dog, press the tape through the coat to the body.
4. 4
   Read the number in inchesWrite the number down. Measure a second time to check that you get the same reading.

No soft tape? Kurgo says a piece of string and a ruler work too. Wrap the string around the chest, mark where it meets, and measure the string against the ruler.

The AKC suggests keeping two fingers under the tape while you measure. A number taken that way runs a little larger than a snug one, which moves you toward the larger size. The harness size tool expects the snug number, and the two-finger check comes later, once the harness is on.

Measure the neck

Measure around the base of the neck, where a collar sits. Kurgo says to wrap the tape just below the narrow part of the neck, right above the shoulders; if you are unsure, feel for the shoulders and measure just in front of them.

Only some brands use the neck. Kurgo asks for both measurements, and rabbitgoo publishes a neck range for every size. Ruffwear, PetSafe and Julius-K9 size their harnesses by chest alone, so for those the neck is only a cross-check.

Check the fit with two fingers

Once the harness is on and adjusted, slide two fingers flat under each strap. They should fit without forcing. The AKC uses this two-finger gap for harnesses, and Ruffwear uses the same test for collars.

• If you cannot fit two fingers, loosen the straps. If the straps are already at their longest, the harness is too small.
• If the straps are at their shortest and there is still far more room than two fingers, the harness is too big.

Measuring a puppy

Fit the harness to the puppy's chest today, not to the dog it will become. A harness bought to grow into is loose now, and a loose harness can slip off. Ruffwear notes that larger breeds can keep growing until about 12 to 18 months.

Measure again whenever the harness is near its largest setting. When a growing puppy is truly between two sizes, Ruffwear suggests the larger one: its example is a puppy with a 17 inch chest, which sits on the line between its XXS (13-17 inches) and XS (17-22 inches), and Ruffwear recommends the XS.

When your dog is between sizes

Ruffwear and PetSafe both say to choose the larger size when a dog falls between two, and the AKC gives the same advice. A larger size has room to tighten, while a small one at its largest setting cannot be let out.

Sizes also mean different chests at each brand. At a 26 inch chest, Ruffwear's Front Range chart says S, PetSafe's Easy Walk says Medium, rabbitgoo's Classic says L and Julius-K9's IDC says M/0. Always compare the number with the chart for the exact harness you are buying.

Weight is a poor substitute for the tape. PetSafe calls its weight ranges only approximate, and Kurgo points out that a 40 pound Bulldog and a 40 pound Greyhound need very different fits.