What size harness does your dog take?
Letter sizes mean different things at different brands. A dog with a 76cm chest is a Julius-K9 “1” and a Ruffwear “M”. Measure once, and read the answer for all of them.
Measure right around the deepest part of the ribcage, just behind the front legs.
6 size ranges overlap here. The marker shows where your dog falls inside each one — nearer the middle means more adjustment room either way.
How to measure
Take a soft tape right around the deepest part of the ribcage, just behind the front legs, and keep it snug against the coat rather than pulled tight. That single number — the girth — is what every brand on this page sizes by. Weight is only a tie-breaker: two dogs at the same weight can differ by 10cm of chest, so where the two disagree, the tape wins.
Why the sizes overlap
Harness ranges are built to overlap so that adjustment straps have somewhere to go. A 65cm chest genuinely falls inside three Julius-K9 sizes. Most calculators pick one and say nothing; this one shows you all of them and where your dog sits in each, because that position is what decides whether you have room to tighten, room to grow, or neither.
Where these numbers come from
Every range is transcribed from the manufacturer’s own published chart — 34 sizes across 5 brands, each recorded with the page it came from and the date it was checked. Where a brand publishes only inches, the conversion is noted in the source. Nothing here is estimated, and nothing is averaged between brands.
- Julius-K9 — IDC Powerharness · 9 sizes · checked 2026-08-19
- Ruffwear — Harness (girth sizing) · 7 sizes · checked 2026-08-19
- PetSafe — Easy Walk Harness · 8 sizes · checked 2026-08-19
- Kurgo — Tru-Fit Smart Harness · 5 sizes · checked 2026-08-19
- Blue-9 — Balance Harness · 5 sizes · checked 2026-08-19
A harness that does not fit is a harness a dog can back out of. If your measurement sits right on the edge of a range, buy the size that leaves adjustment in hand rather than the one that only just closes.