Step-by-step guide to measuring back length and chest girth for the perfect Trail Series fit. Includes full size chart (Sizes 0–8) and breed-specific tips.
The short answer: To size a Trail Series jacket correctly, you need two measurements — back length (base of neck to base of tail) and chest girth (widest point behind the front legs). Always prioritize the larger of the two measurements, and when in doubt, size up. Weight and breed are reference points only — individual dogs vary too much to rely on them alone.
Getting the right fit is the difference between a jacket your dog wears happily on the trail and one that gets returned. This guide walks you through how to measure, how to read the size chart, and what to do if your dog's proportions don't fit neatly into one size.
How to Take the Two Key Measurements
Back Length
Measure along the spine from the base of the neck (where the collar sits) to the base of the tail. Keep the tape flat against the back. Have your dog stand naturally — not stretched out, not hunched.
Chest Girth
Measure around the widest part of the chest, just behind the front legs. Wrap the tape snugly but with two fingers of slack — not tight against the skin.
This is the measurement most people underestimate. When in doubt, re-measure the chest.
PawTrk Trail Series Size Chart
| Size | Back Length (in) | Chest Girth (in) | Leg Length (in) | Weight (lbs) |
|---|---|---|---|---|
| 0 | 13 | 24 | 7 | 15 – 22 |
| 1 | 15 | 27 | 8 | 22 – 28 |
| 2 | 17 | 30 | 9 | 28 – 35 |
| 3 | 19 | 32 | 10 | 35 – 50 |
| 4 | 21 | 35 | 11 | 50 – 61 |
| 5 | 22 | 37 | 12 | 61 – 72 |
| 6 | 24 | 40 | 13 | 72 – 94 |
| 7 | 26 | 43 | 14 | 95 – 115 |
| 8 | 28 | 46 | 15 | 115 – 140 |
When measurements fall between sizes: Always size up. A jacket slightly long in the back can be worn as-is; a jacket too tight in the chest restricts breathing and movement.
Common Breeds by Size (For Reference Only — Always Measure First)
| Size | Common Breeds |
|---|---|
| 0 | Pug, Miniature Schnauzer, small Beagle, small Cavalier King Charles Spaniel, Jack Russell Terrier |
| 1 | French Bulldog (broad chest — check girth), Boston Terrier, Shiba Inu (small), Cocker Spaniel (small), large Beagle |
| 2 | Large Beagle, Corgi (larger build), Standard Cocker Spaniel, Shetland Sheepdog (larger), Mini Goldendoodle (small), Whippet (large) |
| 3 | Border Collie, Australian Cattle Dog, English Springer Spaniel, Standard Schnauzer, Australian Shepherd (smaller build) |
| 4 | Large Border Collie, Australian Shepherd, Boxer (small female), American Pit Bull Terrier (lean build), Portuguese Water Dog |
| 5 | Golden Retriever (small male / medium female), Labrador Retriever (small male / medium female), German Shorthaired Pointer, Collie, Dalmatian, Flat-Coated Retriever, Siberian Husky, Chesapeake Bay Retriever |
| 6 | German Shepherd (large male), Golden Retriever (large male), Rottweiler (female), Doberman Pinscher, Bernese Mountain Dog (small female), Standard Poodle (large male), Weimaraner, Belgian Malinois (large male), Alaskan Malamute (medium) |
| 7 | Rottweiler (large male), Cane Corso (smaller build), Bernese Mountain Dog (large male), Giant Schnauzer, Alaskan Malamute |
| 8 | Great Dane (small female), Newfoundland (female), Saint Bernard (smaller build), English Mastiff (medium male) |
Step-by-Step Measuring Guide
What you need: A soft fabric tape measure. A piece of string + ruler works just as well.
Step 1 — Stand your dog on a flat surface Natural standing position only. Sitting or lying down will throw off both measurements. High-value treats help keep them still.
Step 2 — Measure back length Start at the base of the neck — feel along the spine until you find where the neck meets the shoulders. Measure straight back to the base of the tail.
Step 3 — Measure chest girth Wrap the tape around the widest part of the ribcage, just behind the front legs. Make sure you can fit two fingers underneath before noting the number.
Step 4 — Check both against the chart Both measurements should point to the same size. If they disagree, see the section below.
When Back Length and Chest Girth Point to Different Sizes
This is more common than most people expect — especially in breeds with deep chests, barrel chests, or long bodies.
Chest larger than back length suggests → size up to fit the chest. A jacket that runs slightly long is comfortable. A jacket too tight across the chest is not wearable on a real hike.
Back longer than chest suggests → size up to fit the back. Use the adjustable side closures to take in extra room around the chest.
More than one size of difference between measurements? Reach out to us before ordering at info@pawtrk.com — we'll help you figure out the right call for your dog's specific proportions.
Breed-Specific Notes
French Bulldogs and broad-chested breeds Chest girth almost always determines the size. Size 1 lists French Bulldogs specifically with the note "broad chest — check girth." Don't rely on weight for these dogs.
Double-coated breeds (Husky, Malamute, Bernese Mountain Dog, Samoyed) Add approximately ½ inch to your chest measurement to account for coat volume, particularly if your dog has a full, fluffy coat.
Giant breeds (Great Dane, Newfoundland, Saint Bernard, English Mastiff) Size 8 accommodates back lengths up to 28" and chest girths up to 46", covering dogs from 115–140 lbs. Body proportions vary significantly within these breeds — measure both dimensions carefully.
Long-bodied breeds (Dachshund, Corgi, Basset Hound) Back length often runs larger relative to chest girth. Size up to fit the back and use the side adjusters to dial in the chest fit.
Note for Male Dogs
The Trail Series jacket includes a belly cutout option for male dogs. Follow the cutting guide on the product page before the first wear — this prevents any interference during bathroom breaks on the trail. Worth doing before you head out, not after you're three miles in.
How to Check That the Fit Is Correct
With the jacket on, your dog should be able to walk, trot, and climb without the jacket pulling at the shoulders or bunching under the belly. Run through this quick check:
- You can slide two fingers under any closure point
- The jacket doesn't pull forward when your dog puts their head down
- Your dog can go up stairs normally without restriction through the shoulders
- The jacket lies flat against the back — if it lifts up when they move, it's too short
Frequently Asked Questions
Can I size by weight alone? Weight is a rough guide only. Two dogs of the same weight and breed can differ by several inches in chest girth depending on their build. Always measure — it takes two minutes.
My dog moves too much to measure. Any tips? Measure after a walk when they're calm. Use high-value treats to keep them standing still. If they won't cooperate solo, loop their leash around a doorknob to keep them facing forward while you measure from behind.
Will the jacket fit if my dog wears a harness underneath? Slim, close-fitting harnesses (Y-harness, Roman harness) usually work fine under the Trail Series. Bulky step-in harnesses may not fit cleanly. If you regularly hike with a harness, add about 1 inch to your chest measurement when sizing.
What if I order the wrong size? PawTrk offers easy returns and exchanges. See the Return & Exchange portal for details.
Does the jacket loosen up after a few wears? The 3-layer shell construction holds its shape over time — there's minimal break-in stretch. Measure accurately rather than counting on the jacket loosening.
How do I wash the jacket without losing the waterproofing? Machine wash cold with a technical outerwear detergent (Nikwax Tech Wash works well). Tumble dry on low — the heat reactivates the DWR (durable water repellent) coating. Avoid fabric softener, which clogs the membrane.
The Bottom Line
The right size starts with two measurements: back length and chest girth. Both need to agree — if they don't, size up to fit the larger one.
For hard-to-fit dogs or unusual proportions, email us at info@pawtrk.com before ordering. Getting the fit right the first time means your dog is on the trail sooner.
Shop the Trail Series + Full Fit Guide →
Need more help? Visit our full fit guide with video walkthrough, or contact us directly.
