Harness size guide

How to measure your dog

Use a soft tape measure with your dog standing square on all four legs, not sitting or lying down. If you only have a rigid tape, run a piece of string round instead and measure the string.

Neck. Around the base of the neck where a collar would naturally sit, not high up near the ears. Chest girth. Around the widest part of the ribcage, just behind the front legs. This is the measurement that matters most and the one people most often get wrong by measuring too far back. Neck to tail. Along the spine from the base of the neck to the base of the tail.

Keep two fingers of slack under the tape. A harness should be snug enough not to twist but loose enough to slide two flat fingers underneath.

Why sizes vary so much between brands

There is no standard. One maker’s medium is another’s large, and a deep-chested dog can need a size up from what their weight suggests. That is why this gives you a starting point rather than an answer: always check the specific manufacturer’s chart against your measurements before ordering.

If your dog falls between two sizes, the larger one with adjustment usually works better than the smaller one at full extension.

Fit matters more than size

A badly fitted harness can rub, restrict the shoulder, or be escaped from entirely. Look for straps that sit clear of the armpits, a chest piece that does not cut across the point of the shoulder, and no gaping when your dog moves. Check the fit again after a few wears, and regularly on a growing puppy, where a harness can go from fine to too tight in a fortnight.