Free dog fit tool
Dog Collar Size Chart
This dog collar size chart turns your dog's measured neck circumference into a recommended adjustable collar range, collar width, likely size label, and two-finger fit check. Weight and breed size are optional cross-checks, never a substitute for measuring.
General fit guidance, not veterinary advice. Everything runs in your browser; nothing is sent or stored.
Your dog's measurements
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Quick examples
Recommended collar
Adjustable range to buy
13-18 in
33-46 cm
- Measured neck
- 14 in (36 cm)
- Fit allowance
- +1 1/2 in (4 cm)
- Target collar fit
- 15 1/2 in (39 cm)
- Collar width
- 3/4 in (20 mm)
- Likely size label
- M
- Style and stage
- Flat buckle, adult
Two-finger fit check
Two flat fingers should slide under the buckled collar with light resistance. The collar should not slip over the head when pulled gently forward.
Fit and safety notes
- Flat buckle collars only adjust at fixed holes, so choose a size where your dog's fit lands on a middle hole.
- Trim or tuck excess strap so it cannot catch, and check the buckle and holes for wear.
Your measured neck is the primary sizing input. Brand charts vary, so confirm the product's listed range before buying.
Dog collar size chart
Typical generic labels by neck range. Ranges overlap, as they do across brands. Rows that fit your dog's target are highlighted.
| Size | Inches | Centimeters | Matches your dog |
|---|---|---|---|
| XXS | 6-9 | 15-23 | No |
| XS | 8-12 | 20-30 | No |
| S | 10-15 | 25-38 | No |
| M | 14-20 | 36-51 | Best |
| L | 18-26 | 46-66 | No |
| XL | 22-30 | 56-76 | No |
| XXL | 26-34 | 66-86 | No |
Your target fit: 15 1/2 in (39 cm).
Collar fit and safety guide
Growing puppies
Puppy necks can outgrow a collar within weeks. Check the two-finger fit at least weekly, re-measure every 2 weeks, and replace the collar once it no longer lets out.
Flat buckle and quick-release collars
Best for everyday ID tags. Fit them so two fingers slide under and the collar cannot slip over the head when pulled forward. Tuck in any loose strap end.
Breakaway collars
Built to release if the collar snags, which suits unsupervised time at home. Do not clip a leash to the breakaway buckle unless it has a bypass ring; walk on a harness instead.
Martingale collars
Limited-slip collars sized to the neck itself. When tightened the rings should not touch. Use them on supervised walks only, never in a crate or during play.
When to re-measure
Re-measure after weight change, a seasonal coat change or grooming, if you can fit more or fewer than two fingers, or if you see rubbing, hair loss, or the collar rotating easily.
If you notice rubbing, coughing, or skin irritation around the collar, take it off and ask your veterinarian or groomer to check the fit.
How to measure for a dog collar
- Step 1
Wrap a soft measuring tape around your dog's neck where the collar sits, snug but not tight.
- Step 2
Enter the neck circumference in inches or centimeters.
- Step 3
Optionally add weight, breed size, age stage, collar style, and fit preference.
- Step 4
Select Find collar size to see the adjustable range, width, likely size label, and fit check.
- Step 5
Copy the summary or download the CSV, then confirm the two-finger fit once the collar is on.
No tape? Wrap a piece of string or a phone charger cable around the neck, mark where it meets, and measure it against a ruler.
Dog collar size FAQ
How do I know what size collar my dog needs?
Measure around the neck where the collar sits with a soft tape, then add about two fingers of room: roughly 1 inch for toy dogs, 1.5 inches for most small and medium dogs, and 2 inches for large dogs. Buy a collar whose adjustable range includes that number.
Can I size a dog collar by weight or breed?
Only as a rough check. Dogs of the same weight or breed can have very different necks, so this chart uses weight and breed size to flag a measurement worth rechecking, never to pick the size.
What size collar should a puppy wear?
Choose a lightweight adjustable collar where the puppy's current fit sits near the smallest setting, so it can let out. Check the two-finger fit at least weekly and re-measure every 2 weeks while they grow.
How should a martingale collar fit?
Size a martingale to the neck itself. With the leash slack, two fingers should fit underneath; when the leash tightens, the loop should close snug without the two rings touching, and it must still slide over the head when loose.
What if my dog is between two collar sizes?
Generic size ranges overlap. Compare each product's exact range and pick the one where your dog's target fit lands in the middle for an adult, or near the low end for a growing puppy.