Harness fit is decided by chest girth, not by weight and not by breed. Put a soft tape around the widest part of your dog's ribcage, just behind the front legs, with the dog standing. Then measure the neck where a collar would sit. Enter both below.
Two harnesses, two different charts. The Blacktop is cut for everyday walking and the Ridgeline for carrying kit, and a size in one is not a size in the other — so pick the one you are sizing first. How you measure is the same for both.
Widest point of the ribcage, behind the front legs.
Where the collar sits. Optional, but it catches fit problems.
Only used to make the result easier to read.
Type anything — mixes welcome. Some builds have a known fit quirk we'll flag.
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The size chart this uses
Blacktop Everyday Harness
| Size | Neck base | Chest / girth | Back length |
|---|---|---|---|
| S | 46–51 cm (18–20") | 56–71 cm (22–28") | 24 cm (9.5") |
| M | 46–61 cm (18–24") | 71–89 cm (28–35") | 28 cm (11") |
| L | 53–81 cm (21–32") | 71–102 cm (28–40") | 30 cm (12") |
| XL | 61–76 cm (24–30") | 81–114 cm (32–45") | 33 cm (13") |
Two honest gaps in our supplier's chart for this one. The L chest range starts at the same 28" as M, so on paper it swallows M whole — the calculator takes the smallest size that genuinely fits rather than guess at the figure they meant. And the XL neck range reads shorter than L's, which is the wrong way round. Their dog-weight column is left out altogether because its rows contradict each other. It is all written up on the product page.
Ridgeline MOLLE Harness
| Size | Neck | Chest / girth | Back length |
|---|---|---|---|
| S | 23–31 cm (9–12") | 38–55 cm (15–21.5") | 33 cm (13") |
| M | 30–38 cm (12–15") | 42–70 cm (16.5–27.5") | 40 cm (15.75") |
| L | 35–45 cm (13.75–17.75") | 47–93 cm (18.5–36.5") | 48 cm (19") |
| XL | not published — see note | 52–103 cm (20.5–40.5") | 53 cm (21") |
One honest gap: our supplier's chart lists an XL neck range we're fairly sure is a typo, so we've left that cell blank rather than print a number we can't stand behind. Email hello@redwolfcoshop.com and we'll confirm XL neck fit before you order.
What this tool can't tell you
It reads a size chart. It cannot tell you whether a harness suits your dog's shape, and that is a real limitation rather than a disclaimer.
Two dogs with identical chest measurements can need different harnesses if one is deep-chested and the other barrel-chested — the girth number is the same, the geometry is not. If your dog has a large gap between neck and chest measurements, read harness sizing for deep-chested dogs before ordering anything.
Breed is a hint, never a measurement. We flag build patterns that are common in a breed because they change which harness style works — but a tape around the ribcage beats any breed rule, including ours, and mixed-breed dogs routinely ignore the pattern their looks suggest.
A chart also can't confirm the harness is on correctly once it arrives. Check it against how tight a dog harness should be — two fingers under every strap, tested one strap at a time — and re-check after a few wears, because webbing settles.
The measuring method itself is covered in full in how to measure your dog for a harness, including the mistakes that throw the number off: measuring over thick fur, pulling the tape tight, and measuring the belly instead of the ribcage.