How to Choose Dog Collars for Large Dogs | Fit by Neck, Not Name

Picking a collar for a big dog comes down to one measurement, not a guess. A 90-pound Labrador and a 90-pound Great Dane have completely different neck sizes, so buying by weight or breed label lands most owners at the wrong end of the adjustment range. The fix takes thirty seconds with a soft tape measure, and it keeps your dog comfortable and secure.

Measure the Neck Where the Collar Sits

Wrap a soft tape measure around the base of the neck, right where the collar will rest. That spot sits higher than you might think — just behind the ears and jaw, not down near the shoulders. Pull the tape snug but not tight, then add room for two fingers to slide underneath. That gap is the difference between a collar that chafes and one that slips off.

If the measurement falls between two sizes, every major fitting guide says the same thing: choose the larger size. A collar at the very end of its adjustment range sits awkwardly, and a dog that pulls can pop the buckle. The larger option gives you room to tighten properly.

Large-Dog Collar Sizes Vary by Brand

Brand charts do not agree on what “Large” means. PetSmart lists Large collars for necks 16–26 inches and Extra large for 24–30 inches, associating XL with breeds like Bernese Mountain Dog, Great Dane, Mastiff, Rottweiler, and Saint Bernard. Coastal Pet’s sizing guide uses weight bands instead, listing Large for 50–80 lb dogs with an 18–26 inch collar, and X-Large for 90–150 lb dogs with a 20–28 inch collar.

Ruffwear’s retailer guides work in different bands again, showing large-adjacent ranges like 20–26 inches and 23–26 inches. One brand’s Large can overlap another’s Medium or XL, so check the exact neck range on the package before you buy.

Width Matters More Than You Think

Narrow collars dig into a big dog’s neck when they pull. Most large-dog guides recommend 1.0-inch (25 mm) webbing for bigger sizes because the wider strap spreads pressure across more surface area. Ruffwear uses 25 mm webbing on its larger collars, and retailer charts follow the same pattern. If your dog’s size range offers both narrow and wide options, take the wider one.

Before you buy, confirm the collar’s minimum and maximum neck range. A collar spanning 20–28 inches gives you far more adjustment room than one spanning 24–26 inches, and that slack matters as your dog’s coat thickness changes through the seasons.

Common Mistakes and Safety Checks

The biggest error is buying by breed. A skinny Great Dane and a stocky Rottweiler both carry the “large breed” label, but their necks measure completely differently. Always measure. The second mistake is ignoring width, and the third is forgetting that a collar is not a restraint for a hard puller. If your dog lurches at the end of the leash, pair the collar with a front-clip harness for control. Harness sizing follows chest girth behind the front legs, not neck size, so measure separately.

Run the two-finger check every few weeks. Puppies and young dogs grow fast, and a collar that fit last month may now sit too tight. If it slips over the head easily, it is too loose. Check that the buckle and D-ring show no rust or cracking, and confirm the fit sits high on the neck, not down near the shoulders where it can rub.

FAQs

Should I buy a collar based on my dog’s weight?

Weight is a rough guide at best. Coastal Pet links Large to 50–80 lb dogs and X-Large to 90–150 lb dogs, but neck circumference is the number that actually determines fit. A lean 80 lb dog may need a Large collar while a muscular 80 lb dog needs an XL, so measure the neck and use the chart as a starting point, not a rule.

How tight should a dog collar sit?

A properly fitted collar lets two fingers slide comfortably between the webbing and your dog’s neck. Any tighter and it risks chafing or restricted breathing; any looser and a determined dog can back out of it. Recheck the fit monthly, especially for young dogs still growing into their full frame.

What width collar is best for a large dog?

Look for 1.0-inch (25 mm) webbing on collars for large breeds. The wider strap spreads pressure evenly when the dog pulls, reducing strain on the neck and throat. Narrow collars concentrate force into a thin line and can cause discomfort or coughing in strong pullers.