Quick answer: to measure your dog for a harness, wrap a soft tape measure around two spots: the base of the neck (where a collar naturally sits) and the widest part of the chest (just behind the front legs). Keep two fingers between the tape and your dog, write both numbers down, then match them to the size chart. If your dog sits between two sizes, go up a size.
A harness that fits well is comfortable, hard to slip out of, and gives you real control on the lead. One that doesn't fit can rub under the legs, twist sideways, or let a wriggly dog back straight out of it. The good news: getting it right takes about two minutes.
What you'll need
- A soft, flexible tape measure (a sewing tape is perfect)
- No tape? A piece of string or a phone charging cable, then lay it flat against a ruler
- A few treats, and a helper if your dog won't stand still
- Something to write the numbers on
Step 1: Measure the neck
Run the tape around the lower part of the neck, close to where the neck meets the shoulders. This is where the top strap of the harness sits, which is lower and wider than the very top of the neck behind the ears.
Slide two fingers flat under the tape. It should feel snug, not tight. Note the number in centimetres.
Step 2: Measure the chest
This is the most important measurement. Wrap the tape around the widest part of the ribcage, usually about a hand's width behind the front legs. Make sure the tape sits flat and level all the way round, not angled towards the tummy.
Again, keep two fingers under the tape and note the number.
Step 3: Match your numbers to the size chart
Here is the size guide for the Pelucci 3-Point No-Pull Dog Harness:
| Size | Neck | Chest |
|---|---|---|
| XS | 20.3–27.9 cm | 30.5–38.1 cm |
| S | 28–39 cm | 35.6–55.9 cm |
| M | 30.5–45.7 cm | 45.7–71.1 cm |
| L | 40.6–53.3 cm | 61–96.5 cm |
Chest comes first. If the neck and chest point to different sizes, choose the size that fits the chest, because that is where the harness does most of its work. The neck strap is adjustable to fine-tune the rest.
In between sizes? Size up. A slightly bigger harness can be tightened; one that's too small can't be loosened.
Step 4: Check the fit once it's on
When the harness arrives, adjust the straps and run through this quick check:
- Two-finger rule: you can slide two fingers under every strap, but not your whole hand.
- No rubbing: the straps shouldn't sit tight in the armpits or press on the throat.
- Stays centred: the harness doesn't twist to one side when your dog walks.
- Backing-out test: gently pull the lead forward. If the harness slides over your dog's head, tighten the neck and chest straps a little.
- Free shoulders: your dog can walk, trot and sit normally without the straps restricting the front legs.
Got an escape artist? Our guide on how to stop your dog slipping out of a harness has extra tips.
Common measuring mistakes
- Guessing from weight or breed. Two dogs of the same breed can be very different shapes. Always measure.
- Measuring the top of the neck. That's collar territory. Harness neck straps sit lower, closer to the shoulders.
- Measuring over a fluffy coat too loosely. Press the tape gently into the fur so you measure the dog, not the floof.
- Measuring a puppy once. Growing puppies can change size within weeks. Re-measure every month or so and adjust the straps as they grow.
- Using a metal tape measure. It won't wrap around a curved body and gives a smaller reading.
Tips for wriggly dogs
Measure after a walk, when your dog is calmer. Ask a helper to hold a treat in front of their nose while you measure. Or use the string method: wrap, pinch the string where it meets, then measure the string against a ruler once your dog has wandered off.
Ready to choose?
Once you have your numbers, pick the setup that suits your walks:
- 3-Point No-Pull Dog Harness: the harness on its own
- Harness Walk Set: harness plus a matching lead
- Hands-Free Harness Walk Set: for walks, jogs and coffee runs with both hands free
If the size isn't quite right when it arrives, see our exchange policy for how size exchanges work.
FAQ
Should a dog harness be tight or loose?
Snug but comfortable. You should be able to fit two fingers under each strap. Any looser and your dog may slip out; any tighter and it can rub.
Is chest or neck size more important for a harness?
Chest size. It decides which size to buy; the neck strap is then adjusted to fit.
My dog is between two sizes. Which should I pick?
Go up a size. You can tighten the straps, but you can't make a small harness bigger.
How often should I re-measure my dog?
Every month for growing puppies, and whenever an adult dog gains or loses weight or gets a big haircut.
Can I measure my dog without a tape measure?
Yes. Use string or a cable, mark where it meets, then measure it flat against a ruler.