Most returns in pet clothing come down to one thing: someone guessed a size from a breed name. Breeds vary enormously, two Labradors can be eight kilos apart, and no two manufacturers cut a medium the same way. Five minutes with a tape measure solves it.
What you need
A soft fabric tape measure, a treat, and ideally a second person. A length of string and a ruler will do if you have no tape.
The three measurements
1. Back length
From the base of the neck, where a collar naturally sits, along the spine to the base of the tail. Your dog should be standing squarely on all four legs, not sitting or lying down. This is the primary number for coats.
2. Chest girth
Around the deepest part of the chest, just behind the front legs. Snug enough that the tape does not sag, loose enough to slide two fingers underneath. This is the primary number for harnesses, and the tie-breaker for coats.
3. Neck
Around the neck where the collar sits, again with two fingers of slack. This is the number for collars.
How to read a size chart
Find the row where both your measurements fall inside the range. If they land in different rows, size up.
For a coat, prioritise chest girth. A coat an inch too long is a minor annoyance; one that is tight across the chest restricts the shoulder and your dog will refuse to walk in it.
For a harness, chest girth is the only number that really matters, and adjustability matters as much as the size on the label. Our size guides list the ranges for each product.
Checking the fit once it arrives
The two-finger rule covers most cases: you should be able to slide two fingers flat between the strap and your dog, anywhere it touches. More than that and it will twist or slip; less and it will rub.
Then watch your dog move in it. Look for the coat riding forward onto the neck, a harness strap sitting in the armpit, or your dog shortening its stride. Any of those means the fit is wrong regardless of what the tape said.
Five mistakes worth avoiding
- Measuring over a thick coat on a fluffy dog. Press the tape gently down to the body.
- Measuring a sitting dog. Back length shortens dramatically when a dog sits.
- Pulling the tape tight. You are measuring the dog, not compressing it.
- Using breed as a size. A working Cocker and a show Cocker are different shapes.
- Sizing up for a growing puppy. A loose harness is an escape risk. Buy to fit now and replace it.
Frequently asked questions
Where exactly is the base of the neck?
Put your dog in its collar and start the tape at the back edge of the collar, in line with the shoulder blades. That is the point every size chart means.
My dog is between two sizes. Which do I pick?
Size up, and use the adjusters to take up the slack. Almost no coat or harness can be made bigger, but nearly all can be made smaller.
Can I measure a cat the same way?
Yes, though cats tolerate it for about four seconds. Chest girth and neck are the two that matter, and cat harnesses should be snug: cats are far better than dogs at reversing out of a loose one.
Once you have your numbers, browse dog coats and jackets or collars, leads and harnesses. UK dispatch, delivery from GBP 3.99 and 30-day returns if the fit is not right.