How to Measure Your Dog for a Harness: The Complete Guide
A 10-pound dog becomes a 500-pound projectile in a 50mph crash with an improperly fitted harness.
Most dog owners make critical measurement mistakes that put their pets at serious risk.
Here's what actually works.
Find perfectly-sized harnesses today.
How to Take the 2 Critical Harness Measurements
Step 1: Measure Your Dog's Chest (This Determines Harness Size)
What You Need:
- Soft measuring tape or string + ruler
- Dog treats for cooperation
How to Do It:
- Position your dog: Standing normally, not sitting or lying down
- Find the spot: Right behind the front legs where chest is widest
- Wrap the tape: Around the chest, snug but not tight
- Check placement: Tape should lie flat against fur, not dig in
- Record the number: This is your harness size measurement
Step 2: Measure Your Dog's Neck (For Safety Check)
How to Do It:
- Find the collar spot: Where your dog normally wears their collar
- Wrap measuring tape: Around neck at this location
- Test the fit: You should fit exactly 2 fingers under the tape
- Record the number: Use this to verify harness neck opening
The Critical Fitting Rules
| Dog Size | Finger Test | Special Notes |
|---|---|---|
| Small (XS-S) | Slightly less than 2 fingers | Avoid pressure points |
| Medium | Exactly 2 fingers vertically | Standard fit rule |
| Large (L-XL) | Slightly more than 2 fingers | Extra room for movement |
Breed-Specific Secrets
Body Type Matters:
- German Shepherds: 28-32" chest = XL harness
- Small, boxy dogs: Different needs than long, lean breeds
- Puppies: Size up - they grow fast (12-18 months for large breeds)
Watch this video How to measure a dog for a harness for more details:
The Two-Finger Rule That Actually Keeps Dogs Safe
Chest Measurement is Everything
Your dog's chest girth determines 90% of harness fit success.
Here's the step-by-step process that works:
- Find the widest part of the chest - Right behind the front legs where the ribcage is largest
- Use a soft measuring tape - Not a rigid one that creates discomfort
- Keep it snug but not tight - The tape should lie flat without digging into fur or skin
- Take the measurement while standing - Your dog must be in the same position as when pulling; back straight with head and neck low
The Critical Neck Measurement
When measuring the neck, wrap the tape measure just below the narrow part where she normally wears a collar, right above the shoulders.
For medium-sized harnesses: You should be able to fit two fingers vertically between your dog's neck and the harness.
Small dogs (XS-S): Slightly less than two fingers
Large dogs (L-XL): Slightly more than two fingers
What the Pet Industry Won't Tell You About Sizing
Breed-Specific Measurement Secrets
Different breeds have completely different body proportions.
German Shepherds: Average chest girth between 28 to 32 inches, making XL-size harness the best choice
Small, boxy dogs need different considerations than long, lean breeds.
The Go-Tech harness is not suited for small dogs, hounds, or dogs with a small neck and deep chest. Instead, it works well with athletic dogs who have wide chests.
The Growth Factor Most People Ignore
Puppies grow FAST.
Many larger dogs may not hit their full size and weight till around 12 to 18 months.
Real example: A 3-month-old puppy with a 17-inch chest girth would be right between XXS and XS harness sizes. We recommend sizing up to the XS since their current girth fits within that size range AND the larger size will give them room to grow.
The Harness Types That Actually Matter
When Step-In Harnesses Save the Day
Perfect for dogs that hate having things pulled over their heads.
Step-in dog harnesses make the fitting process stress-free for anxious dogs.
Zero wrestling. Zero drama. Just step in and buckle up.
Vest Harnesses for Ultimate Comfort
Dog vest harnesses distribute pressure evenly across the chest.
This prevents the concentrated pressure points that cause injury during sudden stops or pulling episodes.
No-Pull Harnesses That Actually Work
Literature shows greater leash tension when using a harness compared to collar, but no pull dog harnesses with front clips redirect pulling behavior without neck injury.
The front attachment point naturally discourages pulling by shifting the dog's momentum.
Durable Harnesses for Serious Use
Durable dog harnesses need reinforced stitching and metal hardware.
Look for Gore® Tenara thread, which resists sunlight, saltwater, chemicals, and other outdoor elements.
The Common Measurement Mistakes Killing Dogs
Mistake #1: Using Rigid Measuring Tools
Rigid tape measures cause discomfort and inaccurate readings.
Always use soft, flexible measuring tape or string.
Mistake #2: Wrong Measurement Position
Taking measurements while your dog is lying down or excited gives false readings.
Mistake #3: Ignoring Weight Changes
Dogs gain and lose weight throughout their lives.
Re-measure every 6 months, especially for growing puppies or senior dogs.
Mistake #4: Trusting Size Charts Over Actual Measurements
Sizes can vary within the same brand. So be sure to take measurements of your dog. Always measure the chest's widest part and the neck's thickest part.
Brand loyalty means nothing if the sizing is inconsistent.
How to Know When Your Measurements Are Perfect
The Escape Test
A properly fitted harness should be impossible for your dog to back out of.
If they can slip out, it's too loose regardless of what the measurements say.
The Comfort Check
The harness should be snug but comfortable around the neck, with enough room for two fingers to fit between the harness and your dog's neck.
The Movement Test
Your dog should move freely without restriction.
Ensure the harness doesn't rub against the armpits, and that the lowest part of the neck opening rests at the chest bone.
The Smart Way to Choose Your Harness
Quality dog harnesses from reputable brands offer better sizing consistency.
Look for:
- Multiple adjustment points (minimum 4-5 areas)
- Reinforced stitching at stress points
- Metal hardware over plastic
- Padding at pressure points
- Clear, detailed sizing charts
The Bottom Line
Proper harness measurement takes 5 minutes but prevents a lifetime of problems.
Measure twice, buy once.
Your dog's safety depends on getting this right the first time.
Blog cover photo from Pagerie!
