What size harness does a Newfoundland need?
The breed standard puts a Newfoundland at 45–68kg (99–150lb). Weight alone settles the size at 2 of the 5 brands. 2 brands size by girth only and are left blank rather than guessed.
What that weight means at each brand
| Brand | Size | What it means |
|---|---|---|
| Julius-K9 | 3 | Every Newfoundland in the breed's weight range falls in Julius-K9 3. |
| Ruffwear | measure | Ruffwear sizes by chest girth only and publishes no weight guidance, so a Newfoundland's weight cannot be converted to one of their sizes. Measure the chest and the tool above will answer it exactly. |
| PetSafe | no size made | A Newfoundland is heavier than the largest PetSafe size, which stops at 43.1kg. This brand does not make a harness for this breed. |
| Kurgo | X-Large | Every Newfoundland in the breed's weight range falls in Kurgo X-Large. |
| Blue-9 | measure | Blue-9 sizes by chest girth only and publishes no weight guidance, so a Newfoundland's weight cannot be converted to one of their sizes. Measure the chest and the tool above will answer it exactly. |
Blank entries are deliberate. Ruffwear and Blue-9 publish no weight guidance to convert, and printing a size anyway would be a guess dressed as an answer.
PetSafe publishes weight guidance, but its range does not reach a Newfoundland — there is no size to recommend rather than one we have withheld.
Now measure, and get the exact size
A breed weight range covers both sexes and every build, which is why it spans more than one size almost everywhere. One measurement replaces all of it. Thick water-resistant coat and a very broad chest.
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 a Newfoundland
Take a soft tape right around the deepest part of the ribcage, just behind the front legs. Keep it snug against the coat rather than pulled tight — you should be able to slide two fingers under it. That single number, the chest girth, is what every brand on this page sizes by. Weight is only ever a tie-breaker.
Why the answer is a range, not a number
Every page that hands you one size for a Newfoundland is hiding the same problem: the breed standard covers a 51% spread in weight between the lightest and heaviest adults, and girth varies more than weight does. Two Newfoundlands on the same scale reading can be a size apart. The honest answer is the shortlist above plus the tape.
Other giant breeds
- What size harness does a Rottweiler need?
- What size harness does a Great Dane need?
- What size harness does a Bernese Mountain Dog need?
- What size harness does a Mastiff need?
- What size harness does a Akita need?
- What size harness does a Saint Bernard need?
- What size harness does a Great Pyrenees need?
- What size harness does a Bullmastiff need?
Weight range from the breed standard, read 2026-08-25. Sizes come from each manufacturer’s own published chart — nothing on this page is estimated or averaged between brands.