How to Measure Your Dog for a Harness (And Get the Fit Right First Time)

A harness that doesn't fit properly is worse than no harness at all. Too loose and your dog can escape. Too tight and it causes chafing, restricted movement, and discomfort. Here's how to measure your dog correctly and choose the right size — first time.

The Two Measurements You Need

1. Neck Girth

Measure around the widest part of your dog's neck — typically just below where a collar would sit. Keep the tape snug but not tight. You should be able to slip two fingers underneath.

2. Chest Girth

This is the most important measurement for harness sizing. Measure around the deepest part of your dog's chest, approximately two finger-widths behind the front legs. This is where the harness sits and where most of the adjustment happens.

Tools You Need

• A soft fabric measuring tape (the kind used for sewing)
• A helper to keep your dog still (or a handful of treats)
• A notepad to record the measurements

Step-by-Step Measuring Guide

1. Have your dog stand in a natural, relaxed position — not sitting.
2. Wrap the measuring tape around the widest part of the neck. Note the measurement.
3. Move the tape behind the front legs and wrap it around the deepest part of the chest. Note the measurement.
4. Add 1–2 inches to each measurement to account for comfort and movement.
5. Compare against the harness size chart — if between sizes, always size up.

PetPeek Harness Size Guide

The PetPeek No Pull Dog Harness is available in three sizes:

• Medium: Chest 18"–24" | Neck 14"–20" — suits Border Collies, Cocker Spaniels, Whippets
• Large: Chest 24"–32" | Neck 18"–26" — suits Labradors, Golden Retrievers, German Shepherds, Huskies, Boxers
• X-Large: Chest 30"–40" | Neck 22"–30" — suits Akitas, Giant Schnauzers, Rottweilers, American Pit Bull Terriers

The 2-Finger Rule

Once the harness is on, check the fit using the 2-finger rule: you should be able to slide two fingers under any strap. If you can fit more than two fingers, tighten the strap. If you can't fit two fingers, loosen it. This applies to all four adjustment points on the PetPeek harness.

Signs of a Poor Fit

• Too loose: Harness slides sideways, dog can step out of it, straps hang away from the body.
• Too tight: Visible indentation in fur, restricted shoulder movement, dog seems uncomfortable or reluctant to walk.
• Wrong shape: Straps twist or cross over each other — readjust until they lie flat and parallel.

Getting the fit right takes 5 minutes and makes every walk safer and more comfortable for your dog. If you're unsure, size up and use the adjustment straps to dial in the fit.