Dog Collar Size Chart: How to Measure Your Dog for the Right Fit

By Celine Li, FURRI Editorial Team
Published on October 6, 2026 

Finding the right collar size starts with an accurate neck measurement. Breed, weight, and S/M/L labels can help you estimate where to start, but they do not always determine the final size because sizing ranges can vary across brands and product lines. For a standard flat collar, match your dog’s neck measurement to the product’s listed adjustable range.

Looking for FURRI sizing? Current FURRI collars are M (14–20 in / 36–51 cm) and L (20–26 in / 51–66 cm). See the full FURRI size chart below.

In This Article

• What dog collar size labels and ranges mean
• How to measure your dog’s neck for an everyday flat collar
• Can you choose a dog collar size by breed or weight?
• How to use a dog collar size chart
• FURRI dog collar size chart — current sizes
• What else can affect collar fit?

What Dog Collar Size Labels and Ranges Mean

A dog collar size chart pairs each size label with an adjustable measurement range. Labels such as Small, Medium, and Large are category names; the actual range is what tells you whether a collar can fit your dog.

The same size label can cover different ranges across products. For example, one Medium collar may adjust from 12–18 in, while another Medium may adjust from 14–20 in. That is why you should match your dog’s measured neck circumference to the listed range rather than choose by the size name alone.

How to Measure Your Dog’s Neck for an Everyday Flat Collar

This guide focuses on everyday flat collars. Specialized collars—such as martingales or other training-specific designs—may use different fitting instructions, so always check the guidance for that specific product.

To measure your dog’s neck:

1. Use a soft measuring tape.
2. Measure around your dog’s neck where the collar normally sits. Neck circumference can vary depending on where you measure, so use the collar’s actual resting position rather than measuring higher or lower on the neck.
3. Record the measurement in inches or centimeters.
4. Compare that number with the collar’s listed size range.

If you don’t have a soft measuring tape, wrap a piece of string around your dog’s neck, mark where it overlaps, then lay it flat and measure the length with a ruler.

Can I measure a collar that already fits?

Yes—if your current collar fits well, it can be a useful cross-check. Do not rely on the old S/M/L label alone: different buckle and collar constructions can use different measuring points, and worn collars can change over time.

For a traditional belt-style buckle collar, measure from the buckle’s center bar to the hole your dog currently uses.

For some side-release buckle collars, the measuring points are different. One common method is to measure from the end of the female part of the buckle to the opposite end of the collar, excluding the male part of the buckle.

Whichever method you use, follow the measuring instructions for the collar you are buying.

What about the two-finger rule?

The two-finger rule is useful for checking final fit after the collar is on, but it is not the neck measurement itself. Use the product’s sizing method to choose the size, then check the fit after fastening the collar.

Can You Choose a Dog Collar Size by Breed or Weight?

Breed and weight can help you estimate where to start, but they do not always determine the final size. A 50-pound dog is not automatically a Large, because dogs at the same weight can still have different neck measurements depending on breed, build, age, coat, and individual variation.

If breed or weight guidance suggests one size but your dog’s measured neck circumference falls into another size range, use the neck measurement and the specific product’s sizing chart as your primary guide.

If a product provides its own breed- or weight-based instructions, follow those product-specific directions rather than treating a general breed or weight chart as universal.

What About Collar Width and Bulk?

For standard flat collars, neck circumference is the primary sizing input, while collar width and bulk are separate considerations. As practical examples, Preventive Vet suggests about 3/8 in for a Chihuahua, about 3/4 in for a Beagle, and at least 1 in for larger breeds.

These are examples—not universal cutoffs—but they show why a width that works well on a larger dog may be unnecessarily bulky on a much smaller neck.

Overall collar weight and bulk depend on width, material, and construction. Leather collars tend to be heavier, while nylon and biothane options are often lighter, but the collar as a whole matters more than any single material or gram cutoff. For smaller dogs, avoid unnecessary width or overall bulk.

How to Use a Dog Collar Size Chart

A product page may show three different kinds of information:

• Size label — for example, Medium
• Adjustment range — for example, 14–20 inches
• Collar width — for example, 0.79 inches

These numbers do not mean the same thing. The adjustment range tells you whether your dog’s neck measurement falls within that collar’s adjustable range; collar width describes the width of the strap and should not be confused with the sizing range.

If your dog’s neck measures 18 inches, check which adjustable range includes 18 inches.

In this example, the 14–20 inch range is the appropriate starting point.

FURRI Dog Collar Size Chart — Current Sizes

FURRI collars currently come in two adjustable sizes:

For FURRI collars, compare your dog’s measured neck circumference directly with the listed range; do not add extra inches before choosing a size. At the shared boundary of 20 in / 51 cm, FURRI’s sizing guidance is to choose Large.

The same M/L collar sizing also applies to the collar included in the FURRI Collar & Leash Set.

FURRI currently offers Medium and Large only. If your dog’s neck measurement falls below 14 in / 36 cm or above 26 in / 66 cm, the current FURRI collar sizes do not cover that measurement.

What Else Can Affect Collar Fit?

Neck circumference gives you the starting point, but fit can change as your dog grows, gains or loses weight, or its coat changes. Recheck the measurement and fit when any of these change:

• After a major coat change or grooming: make sure you are measuring the neck rather than just the outer coat, and check the fit again after grooming.
• As a puppy grows: remeasure rather than assuming the same collar setting or size will continue to fit.
• After a noticeable weight change: measure again before assuming the previous setting is still right.

If your dog can back out of a standard flat collar, sizing may not be the only issue. Simply tightening the collar or choosing a smaller size may not be the right solution; consider guidance for a collar design intended to reduce slipping out.

Once you have the right size, the next step is checking the final fit.

Read next: How Tight Should a Dog Collar Be? A Guide to Proper Collar Fit