Dog harness size chart by chest girth
Harness size is one measurement: the girth around the widest part of the rib cage, just behind the front legs. Weight charts for harnesses are a guess; a deep-chested 40 lb Whippet and a barrel-chested 40 lb Bulldog are two sizes apart. Measure, then read the chart.
Harness size from girth
Ruffwear Front Range sizing
| Size | Chest girth | In cm |
|---|---|---|
| XXS | 13–17 in | 33–43 cm |
| XS | 17–22 in | 43–56 cm |
| S | 22–27 in | 56–69 cm |
| M | 27–32 in | 69–81 cm |
| L/XL | 32–42 in | 81–107 cm |
Source: Ruffwear — Front Range harness sizing (manufacturer), checked 2026-10-20. Rule from the same page: "Measurement is around the widest part of the rib cage. In between sizes? Choose the larger size."
How to measure
Stand the dog. Run a soft tape around the chest at its widest point — usually a hand's width behind the front legs — snug but not compressing the coat. Take it twice; coats and breathing move the number by an inch. If the measurement lands on a boundary (27 in, say), the manufacturer's rule is to take the larger size, because a harness that is too small restricts the shoulder and a slightly large one adjusts down. Other makers publish their own charts with different cut-offs; the measuring method is the same, so re-check the girth against the chart of whatever harness you buy.
A fitted harness lets two fingers slide under every strap, sits clear of the armpits by about two finger-widths to avoid chafing, and does not rotate when the leash is pulled sideways. Puppies grow out of harness sizes quickly — expect two or three sizes between eight weeks and adulthood for a medium or large breed — so check the fit every couple of weeks alongside the weigh-ins in the puppy charts.
Why there are no breed harness pages here
Breed standards publish height and weight, not chest girth, and girth varies more within a breed than either. Rather than invent a girth per breed, this site gives the chart and the measuring method. For crate and bed, where manufacturers size by weight and standards publish weight, there are breed pages.