Dog Collar Sizes and How to Measure
Measure your dog's neck with a soft tape and match the brand's chart; a flat collar should pass the two-finger test, and a martingale fits behind the ears.
By Jennifer HunterContributing writer.
On this page
The short answer
Collar sizes are neck ranges in inches, and every brand draws its ranges a little differently. Measure your dog's neck, then read the chart of the exact collar you plan to buy. Names like small or large mean little on their own: a PetSafe small martingale fits an 8 to 12 inch neck, while a PetSafe small breakaway collar fits 10 to 14 inches.
How to measure your dog's neck
- Use a soft tape measure.
- Wrap it around the neck where the collar will sit. For a martingale, PetSafe says to measure around the top of the neck, right behind the ears.
- Keep the tape snug but flat, not pulled tight.
- Read the number and compare it with the brand's chart.
For its KeepSafe breakaway collar, PetSafe tells you to measure the neck and add an inch. Its martingale is different: the measurement equals the collar's size when it is fully tightened, so you do not add anything.
Dog collar size chart (PetSafe examples)
| Collar | Size | Width | Fits neck |
|---|---|---|---|
| Martingale | Petite | 3/8 inch | 5.5 to 8 in |
| Martingale | Small | 3/4 inch | 8 to 12 in |
| Martingale | Medium | 3/4 or 1 inch | 10 to 16 in |
| Martingale | Large | 1 inch | 14 to 20 in |
| KeepSafe breakaway | Small | 3/4 inch | 10 to 14 in |
| KeepSafe breakaway | Medium | 3/4 or 1 inch | 14 to 20 in |
| KeepSafe breakaway | Large | 1 inch | 18 to 28 in |
PetSafe lists sample breeds next to each size, for example Chihuahua and Yorkshire Terrier for the petite martingale and Labrador and Rottweiler for the large. Treat breeds as a hint only; the tape measure decides.
The two-finger fit test
Once the collar is on, PetSafe's walking-gear guide uses the two-finger rule: you should be able to slide two fingers between the collar and your dog's neck, no more and no less.
Martingale vs flat collar
A flat (buckle) collar stays the same size. It is the everyday collar for ID and license tags and suits dogs that already walk on a loose leash.
A martingale (limited-slip) collar has a second, smaller loop. When the dog pulls, it tightens to a set point and then loosens when the pulling stops. PetSafe aims it at dogs whose heads are narrower than their necks, such as Greyhounds and Whippets, which can back out of a flat collar. When a martingale is pulled tight, PetSafe says its two metal rings should touch directly behind the ears.
| Flat collar | Martingale | |
|---|---|---|
| Size on the dog | Fixed | Tightens to a limit |
| Main use | Tags, everyday wear | Dogs that slip out of collars |
| Fit check | Two fingers underneath | Rings touch when pulled tight |
PetSafe's guide also notes that a collar puts leash force on the neck, so for hard pullers, short-nosed breeds or dogs with airway problems it suggests a harness for walks and the collar for tags only.
How we count
Sizes, widths and fitting rules are PetSafe's, from the pages linked under Sources.
Shopping on Wiki Shopping
Collars sit in the pet supplies department. Check the neck range on each listing against your measurement before you buy.