What Size Pet Door Does My Dog Need? The Breed-by-Breed Guide
Buy a dog door one size too small and your dog will squeeze, hesitate, and eventually refuse to use it. Buy the right size and it disappears into daily life. Sizing comes down to two measurements and a flap chart, and because most owners shop by breed, this guide maps the popular breeds in New Zealand and Australia to the right Dogwalk® flap size. Measure your individual dog to confirm: breeds vary, and your dog is the one who has to fit.
Key Takeaways
- Two measurements decide everything: shoulder height and widest body width, each plus 25mm of clearance.
- Four flap tiers cover almost every dog: 203×187mm (toy), 240×180mm (small), 216×250mm (small-medium), and 270×313mm glass / 320×270mm wood (medium-large).
- Between sizes? Always go up, and for puppies, buy for the adult size of the breed.
How to Measure Your Dog
- Width: measure the widest point of your dog (usually across the shoulders or hips) and add 25mm. This must be less than the flap width.
- Height: measure from the top of the shoulders to the chest or belly line (the vertical "body depth" that passes through the flap) and add 25mm. Dogs duck their heads going through, so the flap doesn't need to match their full standing height; the fitting height on the door does that job.
- Fitting height: install the door so the top of the flap sits at least as high as your dog's back, letting them step through with a lowered head rather than crawl.
The tape-measure walkthrough with photos is in the full measuring guide.
Breed-by-Breed Flap Size Chart
| Typical Breeds | Flap Size | Glass Fitting | Wood Fitting |
|---|---|---|---|
| Chihuahua, Yorkshire Terrier, Pomeranian, Maltese, Toy Poodle, Pug, Miniature Dachshund | 203×187mm (maxi) | Maxi pet doors (G-SDD range) | Maxi wood pet doors |
| Shih Tzu, Cavalier King Charles, Jack Russell, Bichon Frise, Miniature Schnauzer | 240×180mm (small) | — (use maxi or intermediate) | W-SDDW / W-SDDB, tunnel W-SDDTW / W-SDDTB |
| Cocker Spaniel, Beagle, French Bulldog, Cavoodle, Whippet, Fox Terrier, Border Terrier | 216×250mm (intermediate) | G-IDDC / G-IDDW / G-IDDB; slim line G-IDDSLC / G-IDDSLW | — (use small or standard by measurement) |
| Labrador, Golden Retriever, German Shepherd, Border Collie, Huntaway, Boxer, Staffordshire Bull Terrier, Springer Spaniel, Standard Poodle, Dalmatian, Vizsla | 270×313mm glass / 320×270mm wood (standard) | G-DDC / G-DDW / G-DDB; slim line G-DDSLC / G-DDSLW | W-DDW / W-DDB |
Giant breeds (Great Dane, Newfoundland, St Bernard, Irish Wolfhound, Mastiff): measure carefully against the standard flap, as the largest individuals exceed it. Contact us with your dog's measurements and we'll advise the best current option for your installation.
The Rules That Prevent a Wrong Buy
- Between sizes: go up. A flap slightly too big costs nothing in daily use; a flap slightly too small gets abandoned by the dog.
- Puppies: buy the adult size. A Labrador pup fits an intermediate flap for a few months and then doesn't. Size for the breed's adult build from day one; puppies learn big flaps just as fast.
- Two dogs: size for the bigger one. Small dogs use big flaps happily; the reverse doesn't work. Same for cat + dog households: the cat will use the dog's flap.
- Weight is a hint, not a measurement. A lean Whippet and a stocky Staffy can weigh the same and need different flaps. The tape measure decides.
- Older or arthritic dogs: fit the door lower so the step-over is smaller, and go a size up for an easier pass-through.
Where the Door Goes Changes the Model, Not the Size
Once you know the flap size, the location picks the model line: glass panels and sliders take the glass fitting range (installed by a glazier via a round cut-out; see the slider guide and toughened glass guide), while timber, PVC and metal doors take the DIY wood fitting range. Full model-by-model specs are in the dog door buyer's guide.
Frequently Asked Questions
The standard flap: 270×313mm in glass (G-DDC/W/B, G-DDSLC/W) or 320×270mm in wood (W-DDW/B). This tier also covers German Shepherds, Golden Retrievers, Boxers, Huntaways and most large breeds.
The intermediate 216×250mm flap (G-IDDC/W/B dual glaze or G-IDDSLC/W slim line) suits most spaniel-size dogs. If your individual dog measures near the top of the range, step up to the standard flap.
No. Buy the adult size immediately. Puppies learn full-size flaps within days, and you avoid paying for a second door and a second cut-out six months later. Size from the breed's typical adult measurements in the chart above.
Yes. Cats use larger flaps without issue, so one dog-size door serves a mixed household. The trade-off: a big flap can't selectively exclude neighbourhood cats. If that's a problem at your place, add a multi-magnetic cat door for the cat and keep the dog door locked when needed. See cat door vs dog door.
Set the top of the flap level with or slightly above your dog's back height, which puts the step-over low enough to walk through with a dipped head. For glass installations the glazier confirms clearances from panel edges; the fitting instructions included with every door give the exact template.
On-the-limit means the next size up. The 25mm clearance rule exists so the dog passes through comfortably at a walk; a flap they touch on both sides every trip is a flap they'll stop using. If you're at the top of the standard flap, contact us before buying. The tolerance thinking runs both ways: on the door itself, the flap-to-body gap is machined to next to zero and finished with a brush seal, so a correctly sized flap seals as tightly as it swings freely.
Skip the chart: get the exact model
Enter your dog's two measurements and your door or glass type. The door finder returns the right Dogwalk® model in under a minute.
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