How to Measure Dog Collar Size and Get the Right Fit

Quick answer

Measure your dog's neck at its widest point with a soft tape, then add two fingers' width (about 1–2 inches) for comfort. Choose a collar whose adjustable range includes that measurement, and always recheck the fit after a few days of wear.

Gather the right tools before you start

A flexible cloth tape measure works best because it follows the curve of the neck. If you don't have one, use a piece of string or a shoelace, then lay it flat against a ruler. You'll also want a treat or two to keep your dog steady and a second pair of hands if your dog is wiggly.

Measure the neck at its widest point

The widest point is usually just behind the ears and above the shoulders, where the neck meets the head. Wrap the tape snugly but not tight—you should be able to slide one finger underneath. Write down the measurement in inches. If your dog has a thick coat, measure over the fur as the collar will sit on top of it. For puppies, measure every two weeks during growth spurts; a collar that fit last month may already be too snug.

Add the two-finger rule for comfort

A common mistake is buying a collar that matches the exact neck measurement. That leaves no room for movement, breathing, or a full meal. Add 1–2 inches to your measurement, or simply ensure you can fit two fingers between the collar and your dog's neck once it's on. This is the right collar fit for dogs: snug enough that it won't slip over the head, loose enough that it doesn't press on the throat.

Check the collar size chart and adjustable range

Collar sizes vary by brand, so never assume a 'medium' is the same everywhere. Look for the collar's adjustable range—for example, 14–20 inches—and pick the size that includes your dog's neck measurement plus the two-finger allowance. If your dog is between sizes, size up rather than down. An adjustable dog collar with a buckle and several holes gives you the most flexibility as your dog's weight or coat changes with the seasons.

Test the fit and watch for warning signs

Once the collar is on, do a quick check: you should be able to fit two fingers under the strap, and the collar should not slide over your dog's head when they pull backward. Watch for hair loss, redness, or constant scratching around the neck—these mean it's too tight. If the collar dangles low enough for a paw to slip through, it's too loose and could catch on something. For puppy collar sizing, start with a lightweight adjustable collar and check the fit weekly until growth slows.

Step-by-step collar sizing

1. Measure the neck: Wrap a soft tape around the widest part of the neck, just behind the ears. Keep it snug but not tight. Write down the number in inches.
2. Add two fingers: Add 1–2 inches to your measurement, or ensure two fingers fit under the collar once it's on. This prevents choking and allows for breathing and movement.
3. Match to the size chart: Find the collar size whose adjustable range includes your dog's neck measurement plus the two-finger allowance. When in doubt, size up—never down.
4. Test the fit: Put the collar on and check that it doesn't slide over the head, but isn't tight enough to leave marks. If it slides off or leaves red marks, adjust or exchange.
5. Recheck regularly: For puppies, measure every two weeks. For adults, check monthly and after any weight change. A well-fitted collar is one you barely notice—until you need it.

Product facts that help with sizing

• Good Dog Canvas Frisbee Toy: Good Dog Canvas Frisbee Toy: 9" x 9" x .5", 100% cotton canvas outer with cotton-polyester rope tugs. A flat, lightweight toy like this is easy to toss and tug, making it a good reward during collar-fit training sessions.
• Modern Dog Bowl Set - Natural: Modern Dog Bowl Set - Natural: made from 30% recycled plastic. A sturdy bowl set keeps mealtime consistent, which helps you monitor your dog's weight—an important factor in collar sizing.