What size collar does your dog need? This free dog collar size calculator turns your dog’s neck measurement and weight into a recommended collar size, length, and width, draws a live neck diagram, and adds tools for puppies, breeds, collar types, and a two-finger fit test, so you buy the right collar once.
5 Tools
Size calculator, puppy planner, breed finder, type picker, and fit test
+1 to 2 Inches
Extra length to add to your dog’s neck measurement
Two Fingers
The classic fit check: two fingers should slide under the collar
Middle of the Range
Pick a collar that fits your dog near the center of its adjustment
Weekly Puppy Checks
Growing necks outgrow collars fast, so recheck often
Guides Only
Brands differ, so always check the maker’s adjustable range
A collar should be secure enough to hold ID tags and stay on, yet loose enough that your dog breathes, eats, and sleeps comfortably. Too tight can irritate skin and strain the neck; too loose can slip over the head. Pair your result with our Dog Crate Size Calculator, Dog Age Calculator, Dog Weight Calculator, and Dog Exercise Calculator. For general gear and training advice, the American Kennel Club and the ASPCA publish beginner-friendly guides.
Free Dog Collar Size Calculator
Enter your dog’s neck measurement and weight. The calculator adds the right amount of room, finds the collar size whose adjustable range fits best, suggests a collar width, and draws your dog’s neck with the collar so you can see the fit.
Clinical Note: Collar sizes and widths are general guides, and manufacturers measure differently. A collar that causes coughing, gagging, hair loss, or skin redness is too tight. Ask your veterinarian about your dog if there are neck, spine, eye pressure, or breathing concerns.
Puppy Collar Growth Planner
Puppies can outgrow a collar in a few weeks. Choose your puppy’s age and expected adult size, optionally add a measured neck, and see the estimated neck size now, the collar size to buy, and roughly when to upsize.
Collar Size by Breed: Quick Finder
Not sure of your dog's neck size yet? Search a breed to see the usual adult neck range and a matching collar size. Breed averages are a starting point, so measure your own dog and use the calculator above.
Dog Collar Size Chart by Neck, Weight, and Breed
This dog collar size chart lists typical adjustable ranges, the neck sizes they suit, a general width, and example breeds. Use neck measurement first and weight second, because a lean Greyhound and a stocky Bulldog can weigh the same with very different necks.
| Size | Collar Range | Dog Neck | Typical Weight / Width | Example Breeds |
|---|---|---|---|---|
| XXS | 6–9 in (15–23 cm) | 5–8 in | Under 5 lbs · 3/8 in | Teacup Yorkie, tiny Chihuahua |
| XS | 8–12 in (20–30 cm) | 7–11 in | 5–12 lbs · 3/8–5/8 in | Maltese, Pomeranian, Yorkshire Terrier |
| S | 10–14 in (25–36 cm) | 9–13 in | 10–25 lbs · 5/8–3/4 in | Shih Tzu, Pug, Miniature Poodle |
| M | 14–20 in (36–51 cm) | 13–18 in | 25–55 lbs · 3/4–1 in | Beagle, Cocker Spaniel, Border Collie, Corgi |
| L | 18–26 in (46–66 cm) | 17–24 in | 50–85 lbs · 1–1.5 in | Labrador, Golden Retriever, German Shepherd, Boxer |
| XL | 22–32 in (56–81 cm) | 21–30 in | 80–120 lbs · 1.5–2 in | Rottweiler, Bernese Mountain Dog, Newfoundland |
| XXL | 28–38 in (71–97 cm) | 26–36 in | Over 110 lbs · 2 in | Great Dane, Mastiff, Saint Bernard |
Brands list sizes differently, and padded or leather collars can shrink the usable range. Check our Dog Weight Calculator to see whether your dog is at a healthy weight, since weight change can shift neck size, and our Dog Age Calculator for your dog's life stage.
How to Measure Your Dog's Neck for a Collar
You need a soft tape measure and a treat. It takes about a minute and is more accurate than guessing from breed or weight.
| Step | What to Do | Tip |
|---|---|---|
| 1. Use a Soft Tape | Use a sewing tape, or string you can lay against a ruler. | A rigid metal tape reads wrong around fur. |
| 2. Find the Spot | Measure where the collar naturally sits, high on the neck. | Sighthounds wear collars higher, behind the ears. |
| 3. Wrap Snugly | Hold the tape snug against the fur but not pressing the skin. | Keep your dog standing relaxed, head level. |
| 4. Add Room | Add 1 inch for dogs under 15 lbs, 2 inches for larger dogs. | Add up to 3 inches for very thick coats. |
| 5. Match the Range | Pick a collar whose range puts your target near the middle. | Use the calculator above. |
| 6. Test the Fit | Slide two fingers under the collar. | Use the Collar Fit Test below. |
For a puppy that is still growing, ask your veterinarian to estimate adult size. The American Veterinary Medical Association offers general pet-care guidance, and the Merck Veterinary Manual is a trusted reference for anatomy and neck-related health topics.
Which Type of Collar or Harness Is Right for Your Dog?
Size is only half the decision. Flat collars, martingales, harnesses, and breakaway collars suit different dogs and jobs. Pick how you will use it and your dog's head and neck shape.
Collar Fit Test: Is Your Dog's Collar the Right Size?
Already own a collar? Check your dog while wearing it and tick every statement that is true. The test tells you whether it is too tight, too loose, or about right.
Common Collar Sizing Mistakes and How to Fix Them
Most collar problems come from a few easy-to-avoid errors. The Humane Society of the United States and the American Animal Hospital Association offer further pet-care guidance if you have concerns about equipment or comfort.
| Mistake | Why It Matters | Fix |
|---|---|---|
| Buying by Weight Only | Lean and stocky dogs of the same weight have different necks. | Measure the neck first, then check weight. |
| Measuring Too Tight | No room means a collar that rubs or restricts breathing. | Add 1 to 2 inches and test with two fingers. |
| Skipping Thick Coats | Fur hides the true size and compresses over time. | Measure over the fur and add extra room. |
| Ending at the Collar's Limit | A dog at the end of the range has no room to adjust. | Choose a size that centers your dog's measurement. |
| Not Rechecking Puppies | Necks grow quickly and collars become tight in weeks. | Check weekly with the Puppy Collar Planner. |
| Leaving Collars on in Crates | Tags and rings can snag on crate bars. | Remove it or use a breakaway collar. See our Dog Crate Size Calculator. |
| Using a Collar for a Puller | Constant tension strains the neck. | Try a well-fitted front-clip harness and ask a trainer. |
Weight changes affect fit too. Track it with our Dog Weight Calculator, and keep your dog active with the Dog Exercise Calculator. Talk to your veterinarian if your dog's neck size changes suddenly, since swelling can signal a health issue.
Frequently Asked Questions
Measure around the base of your dog's neck where the collar sits, then add about 1 inch for dogs under 15 pounds or about 2 inches for larger dogs. Choose a collar whose adjustable range puts that number near the middle. You should be able to slide two fingers between the collar and your dog's neck.
A flat collar should be snug enough that it cannot slip over your dog's head but loose enough to slide two fingers underneath. If your dog coughs, gags, or has rubbed fur or red skin under the collar, it is too tight.
Most adult Labradors have a neck of about 18 to 22 inches and fit a large collar with an adjustable range around 18 to 26 inches. Measure your own dog, because neck size varies with build and coat.
Check a young puppy's collar weekly, since necks can grow noticeably in a few weeks. Many owners move to every two weeks after about four months and monthly after about eight months. Always repeat the two-finger test.
A flat collar is ideal for ID tags and everyday wear. Many vets and trainers suggest a well-fitted harness for walking dogs that pull, flat-faced breeds, small dogs with delicate tracheas, or dogs with neck problems. Ask your veterinarian about your dog.
Width should scale with your dog. As a general guide, dogs under 10 pounds suit about 3/8 to 5/8 inch, 10 to 25 pounds about 5/8 to 3/4 inch, 25 to 50 pounds about 3/4 to 1 inch, 50 to 80 pounds about 1 to 1.5 inches, and over 80 pounds about 1.5 to 2 inches.
Behind the Research: How We Built This Dog Collar Size Calculator & Guide
At Mondo Paws, our mission is to give pet owners practical, carefully researched tools. To create this calculator and collar guide:
- Built on the Standard Sizing Rule: The calculator uses the widely taught method of measuring the neck where the collar sits, adding about two fingers of room, and matching the result to common adjustable collar ranges. Results are estimates and brands vary.
- Cross-Referenced Trusted Resources: Gear and pet-care guidance was checked against the American Kennel Club, the American Veterinary Medical Association, the ASPCA, the American Animal Hospital Association, and the Merck Veterinary Manual.
- Safety Context: Collar-versus-harness advice reflects common veterinary and trainer guidance, and we recommend asking your vet if your dog has neck, spine, or breathing concerns.
- Interactive Tools, Not Guesswork: Every widget runs in your browser and uses only the numbers you enter. Nothing is stored or sent anywhere.
Final Thoughts
The right collar is snug but comfortable: it stays on, holds ID tags, and leaves room for two fingers. Use our Dog Collar Size Calculator for the main answer, the puppy planner while your dog grows, and the fit test every few weeks. Keep supporting your dog's overall health with our Dog Age Calculator, Dog Weight Calculator, Dog Exercise Calculator, and Dog Crate Size Calculator.
Remember to add an ID tag with your phone number, keep microchip details current, and contact your veterinarian if your dog shows signs of neck pain, coughing, or skin irritation.
