Two measurements, one tape measure, ninety seconds. Here's how to size a dog harness correctly the first time, and what to do when your dog falls between sizes.
Zanna holds still for about four seconds. I know the number because I have measured her more times than I want to admit, and four seconds is what a corgi gives you before the tape measure becomes a toy.
Four seconds is enough. You only need two measurements, and only one of them decides the size.
What you need
A soft tape measure, the kind used for sewing. If you don't have one, use a piece of string and hold it against a ruler afterward. Do not use a metal construction tape. It won't sit flat against a curved chest and it will read short.
Measure your dog standing up, not sitting. A sitting dog's chest reads differently than a walking dog's chest.
Measurement 1: chest girth
This is the number that matters most.
Find the widest part of your dog's ribcage, which sits just behind the front legs. Wrap the tape all the way around, keeping it level with the ground. Pull it snug against the fur but not tight enough to compress the ribs.
You should be able to slide two fingers flat under the tape. That's the fit you're aiming for.
Measurement 2: neck girth
Measure around the base of the neck, where a collar naturally sits, low and toward the shoulders. Not up high near the ears.
Same rule: snug, two fingers underneath.
Match your numbers to a size
Here's the sizing on the Teddy Harness:
| Size | Neck | Chest |
|---|---|---|
| Small | 13.77 to 17.92 in | 16.14 to 21.25 in |
| Medium | 15.35 to 19.68 in | 18.11 to 23.62 in |
| Large | 16.53 to 21.65 in | 22.44 to 31.49 in |
Notice the ranges overlap. That's deliberate, and it's why the chest measurement decides the size, not the neck.
When your dog falls between sizes
Size up. Always.
An adjustable harness can be tightened down. It cannot be made bigger. If your dog measures a 21-inch chest, which lands in both Small and Medium, take the Medium and adjust it in.
The exception is a puppy who is clearly still growing. Then size up twice and expect to buy again in a few months, because a harness that's too big now is a harness your dog can reverse out of on a busy street.
Check the fit before the first real walk
Put the harness on inside the house. Adjust the straps until you can fit two fingers flat under every strap, but no more than that.
Then do this: grab the harness at the shoulders and pull gently backward, the way a startled dog would. If the harness slides toward the head or the front legs slip out, it's too loose. Tighten and test again.
Let your dog wear it around the house for ten minutes before you clip a leash on. Watch for rubbing behind the front legs, which is where chafing starts.
A harness that fits is one you stop thinking about. You check it monthly, you adjust it when the coat changes, and otherwise it just goes on. Four seconds, no negotiating.
Common questions
Should I measure over the fur or under it?
Over the fur, snug. For a very thick double coat, take the measurement snug and don't add extra room. The coat compresses under a harness.
My dog's neck is bigger than the chest range for that size. Now what?
Go by chest. The neck opening on the Teddy Harness is adjustable and has more give than the chest panel.
How often should I re-measure?
Puppies, every month until they're full grown. Adult dogs, whenever their weight changes noticeably or when you buy new gear.
Does the harness come with a leash?
Yes. It ships with the Everyday Walk Leash. If you want the walking bag too, the Complete Walk Kit saves $10.99 over buying the three separately.