Tools
What size harness does my dog need?
Two measurements, one maker's published chart at a time. There is no universal dog size.
Read the maker's chart
Step 1 — whose chart are we reading?
One measurement: a soft tape around the widest part of the rib cage, just behind the front legs. Ruffwear publishes no neck range for this harness, so the girth is the whole answer.
Enter the chest girth and we will read them off Ruffwear Front Range Harness's published chart. The full chart is printed below either way.
A size chart is where a fitting starts, not where it ends. We research; we do not own these harnesses and we do not test them on a dog, so nothing here is a claim about escape resistance, strength or safety - only a reading of the size chart the maker publishes. When it arrives, check it on the dog: two fingers should slide flat under every strap, nothing should sit on the point of the shoulder, and a dog who can back out of it is the wrong size or the wrong shape of harness, whatever the chart said.
Nothing you enter here leaves your browser, and nothing is saved. Every chart on this page is printed in full below, so the answer is checkable without running this at all — jump to the charts.
How to take the two measurements
Chest girth, standing
A soft tape around the deepest part of the rib cage, immediately behind the front legs, with the dog standing rather than sitting. Snug against the coat, not pulled tight. Take it twice: a dog who leans into the tape gives a smaller number the second time, and the larger of the two readings is the one to trust.
Neck, at the base
Where a collar naturally sits when the dog is relaxed, low on the neck, not up under the jaw. Only some makers publish a neck range. Where they do, this is usually the measurement that separates two sizes whose chest ranges overlap.
Then read one chart, not an average of them
Every chart below is transcribed from the maker's own page, opened on 2026-09-07. We do not interpolate between rows and we do not average across brands: if no published row covers your dog, the honest answer is that no published row covers your dog, and a different harness is the fix.
A worked example: a thirty-pound spaniel
- Chest girth, measured behind the front legs: 24 inches. Neck, at the base: 17 inches.
- Ruffwear Front Range: 24 inches falls in the Small row (22 to 27 inches). Ruffwear publishes no neck range, so the girth is the whole decision and the answer is Small.
- Julius-K9 IDC: 24 inches falls in two published rows, Mini (20 to 26.5) and Size 0 (23 to 30). Mini puts the dog nearer the middle of its adjustment range, so Mini first and Size 0 if the coat is thick.
- rabbitgoo: 24 inches falls in the M, L and XL chest ranges. The neck decides it - 17 inches clears M (16 to 21.8) but is under L (18 to 25.8), so M.
- Three makers, three different size names, one dog. That is why this tool reads one chart at a time and never blends them.
The published charts, in full
Every row below is the maker's own. Where a column is missing it is because they do not publish it — we have not filled a gap with an estimate of ours.
Ruffwear Front Range Harness
What decides the size: Girth — the circumference around the widest part of the rib cage.
Ruffwear's own instruction for a dog between two sizes is to choose the larger one.
| Size | Chest girth | Maker's weight note |
|---|---|---|
| XXS | 13 to 17 in | none published |
| XS | 17 to 22 in | none published |
| S | 22 to 27 in | none published |
| M | 27 to 32 in | none published |
| L/XL | 32 to 42 in | none published |
Source: Ruffwear — Front Range Harness, published size chart, opened 2026-09-07.
Julius-K9 IDC Powerharness
What decides the size: Chest circumference. Julius-K9 lists a weight beside each size as a secondary reference only.
Julius-K9's sizes overlap on purpose, and the harness adjusts within its row. Where two rows cover your dog, the smaller one is closer to the middle of its adjustment range; a heavily coated dog is the usual reason to go up.
| Size | Chest girth | Maker's weight note |
|---|---|---|
| Baby 1 | 11.5 to 14 in | 2 to 6.5 lb |
| Baby 2 | 13 to 17.5 in | 4.5 to 11 lb |
| Mini-Mini | 15.5 to 20.5 in | 9 to 15.5 lb |
| Mini | 20 to 26.5 in | 15.5 to 33 lb |
| Size 0 | 23 to 30 in | 31 to 55 lb |
| Size 1 | 26 to 33.5 in | 50.5 to 66 lb |
| Size 2 | 28 to 37.5 in | 61.5 to 88 lb |
| Size 3 | 32.5 to 46.5 in | 88 to 154 lb |
| Size 4 | 38 to 54.5 in | 154 to 198 lb |
Source: Julius-K9 — IDC Powerharness size chart, opened 2026-09-07.
rabbitgoo No-Pull Harness
What decides the size: Both. rabbitgoo publishes a neck range as well as a chest range, and its own guidance is not to choose by weight alone.
rabbitgoo's rows overlap heavily on chest, so on most dogs it is the NECK range that decides which size is right. That is the disagreement this tool exists to surface.
| Size | Chest girth | Neck | Maker's weight note |
|---|---|---|---|
| XS | 11.6 to 18.5 in | 10.2 to 13.5 in | none published |
| S | 13 to 23.5 in | 13 to 18.5 in | none published |
| M | 15 to 27.8 in | 16 to 21.8 in | none published |
| L | 17 to 33.4 in | 18 to 25.8 in | none published |
| XL | 21 to 38 in | 23 to 35 in | none published |
Source: rabbitgoo — dog harness size and wear guide (ControlPro series), opened 2026-09-07.
Two harnesses we stock and could not chart
Both of these are on our shelves and neither is in the sizer, for the same reason: we could not open a page where the maker publishes the numbers. Copying a chart off a retailer listing would look identical on the page and would be a transcription of a transcription, which is the version nobody goes back and corrects.
PetSafe Easy Walk Harness
PetSafe's support page gives the measuring method and the between-sizes rule (match the girth, or go up) but renders its chart as an image we could not read. Measure the girth behind the front legs and check it against the chart on the box or the listing.
Kurgo Tru-Fit Smart Harness
Kurgo's product page points at a size chart we could not open on the date below. Their page does state that the dog modelling a Large measures sixteen inches at the neck and twenty-eight at the chest, which is a useful anchor and not a chart.
Both live on the everyday harness shelf, where the rest of what we know about them is written up.
Questions people ask before they measure
- Where do I measure the girth?
- Around the deepest part of the rib cage, immediately behind the front legs, with the dog standing. Keep the tape snug against the coat rather than pulled tight, and take it twice - a dog who leans into the tape gives you a smaller number the second time.
- Where do I measure the neck?
- At the base of the neck, where a collar naturally sits when the dog is relaxed, not high up under the jaw. Only some makers publish a neck range; where they do, it is usually the measurement that decides between two sizes whose chest ranges overlap.
- My dog is between two sizes. Up or down?
- Follow the maker, because they differ. Ruffwear says to choose the larger size. PetSafe says to go larger or to match the girth. Julius-K9's rows overlap by design and the harness adjusts within a row, so the smaller row often sits nearer the middle of its adjustment. When the maker says nothing, the safer default on a growing dog is the larger size with more strap to let out.
- Can I size a harness from my dog's weight?
- Not reliably. rabbitgoo says in its own guide not to choose by weight alone, and Julius-K9 prints weight only as a secondary reference beside the chest range. Two dogs of the same weight can be four inches apart at the chest, which on most of these charts is a whole size.
- Is a harness safer than a collar?
- That is a question for your vet or a trainer who has watched your dog walk, not for a size chart. We do not test equipment and we do not make safety claims about it. What a chart can tell you is whether a given harness comes in a size that fits your dog at all, which is the question this page answers.
- Does this work for a car harness?
- No, and deliberately so. A restraint sold for use in a car is fitted to a crash-test protocol and to a specific vehicle anchor, and reading its size off a walking-harness chart would be the wrong kind of confident. Follow the maker's own fitting instructions for anything used in a vehicle.
What this page is not
A size chart is where a fitting starts, not where it ends. We research; we do not own these harnesses and we do not test them on a dog, so nothing here is a claim about escape resistance, strength or safety - only a reading of the size chart the maker publishes. When it arrives, check it on the dog: two fingers should slide flat under every strap, nothing should sit on the point of the shoulder, and a dog who can back out of it is the wrong size or the wrong shape of harness, whatever the chart said.