Guide · · Updated · 3 min read
How to measure your dog or cat for a pet door
Breed charts get pet doors wrong. Two measurements get them right. Here is exactly what to measure, what the numbers mean, and which door they point to.
By the Pet-Tek International team, Auckland — designers of Catwalk® and Dogwalk® since 1999.
Every pet-door return we have ever processed came from a breed chart. “Suits spaniels” tells you nothing about your spaniel, and it is the dog in front of you that has to fit through the hole. Two measurements take two minutes and settle it.
Measuring a dog
Stand the dog square on a hard floor, weight on all four feet. You need two numbers.
- Shoulder height. Floor to the top of the shoulder blade (the withers), with a tape held straight. This is the number that picks the door.
- Width. The widest point of the chest or the hips, whichever is bigger. Add 25 mm; the opening must be at least that wide.
Then one more for the installer: belly height, floor to the stomach. That is where the bottom of the opening goes, so the dog steps through instead of crawling.
What the shoulder number means
| Shoulder height | Door | Usable opening |
|---|---|---|
| Up to about 360 mm, wooden door | Dogwalk® Small Slim Line / Small Tunnel | 180 × 227 mm |
| Up to about 380 mm, glass | Dogwalk® Intermediate Dual Glaze / Slim Line | 216 × 237 mm |
| 450–500 mm | Dogwalk® Medium Dual Glaze / Slim Line / Wood-Fitting Medium | 270 × 300 mm |
| Small dog or large cat, to about 300 mm | Catwalk® Maxi | 187 × 190 mm |
Between sizes? Go up. A dog ducks through a slightly big opening without thinking; a slightly small one gets refused.
Measuring a cat
Cats are forgiving, but big breeds are not small cats. Measure the width at the shoulders and the depth from the top of the shoulders to the bottom of the chest, add 25 mm to each, and both numbers must fit inside the opening.
- Most cats to about 7 kg: Catwalk® Standard (glass) or Wood-Fitting Slim Line — 165 × 180 mm.
- Anything over 7 kg, or a long, big-framed cat: Catwalk® Maxi — 187 × 190 mm.
- Selective entry: Multi-Magnetic (155 × 157 mm) or the SureFlap Microchip Cat Flap (142 × 120 mm — print its free size tester first).
Fit a cat door with the bottom of the opening 100–150 mm off the floor.
Two pets, one door
Size for the biggest animal, fit at the smallest one’s belly height. The Maxi exists for the large-cat-small-dog household. A big dog and a cat share a Medium dog door without complaint; what the cat will not do is jump up to a dog’s belly height, so keep the opening low.
Puppies and kittens
Buy for the adult. Breed-standard adult shoulder height is the one time a breed table is useful: look up the adult height, pick the door, and fit it at the adult belly height with a step outside until the puppy grows into it.
Still not sure?
Find your door asks for the measurement and the door type and names the model. Or email a photo of the pet next to a tape measure to info@petnest.co.nz.
Quick answers
What size dog door do I need?
Measure from the floor to the top of your dog's shoulder blade. Up to about 380 mm is the Dogwalk Intermediate, around 360 mm the Small wood-fitting, 450–500 mm the Medium. The opening should also be 25 mm wider than the dog's widest point.
How high should a pet door be off the floor?
The bottom of the opening sits at the animal's belly height: 100–150 mm for a cat, floor-to-stomach for a dog. The pet steps through rather than climbs or crawls.
Can a cat and a dog share one pet door?
Yes. Size for the bigger animal and fit the door at the smaller one's belly height. The Catwalk Maxi was made for large cats and small dogs together; a cat will use a Medium dog door happily.
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