How to Measure Your Pet for a Pet Door — Get It Right First Time
Choosing the wrong size pet door is one of the most common — and easily avoided — mistakes pet owners make. Too small and your pet won't use it. Too large and you'll lose heat and security. This guide walks you through exactly how to measure your cat or dog for a pet door, so you get it right first time.
- Measure shoulder height (top of shoulders to ground) with your pet standing on all four legs — this is your minimum flap height.
- Measure chest width at the widest point of the body — this is your minimum flap width.
- Add 25mm (1 inch) to both measurements for comfortable clearance, then match against the flap opening dimensions on the product page.
Why Getting the Size Right Matters
A pet door that's the wrong size creates real problems. If the opening is too narrow or too short, your pet will hesitate, struggle, or simply refuse to use it — especially cats, who are particularly sensitive to feeling restricted. If it's too large, you're letting in cold air, wind, and potentially unwanted visitors.
The good news is that measuring correctly takes less than five minutes and requires nothing more than a soft tape measure. Do it once, do it properly, and your pet door will work perfectly for years. According to the RSPCA Australia, ensuring your cat can move freely through any access point is an important part of their environmental enrichment and wellbeing.
The Two Measurements You Need
You need two measurements from your pet — their height and their width. Both should be taken with your pet standing naturally on all four legs.
Measuring height — top of shoulders to ground
Measuring width — widest point of chest or hips
Pro tip: Always measure your pet standing up, not lying down or sitting. And if your pet is still growing, measure them at their expected adult size — or size up to the next model to future-proof your purchase.
What About Weight?
Weight is a useful secondary guide — particularly for cats, where breed standards give a good indication of typical body dimensions. Our interactive size calculator uses your pet's weight as the primary input and cross-references it against the flap dimensions of each model in our range.
However, weight alone is not enough. A lean, long-limbed cat and a stocky, short cat of the same weight can have very different measurement profiles. Always verify with physical measurements before finalising your choice.
Measuring for Cats vs Dogs
Measuring for Cats
- Measure height at the shoulder — most cats 20–30cm
- Measure width at the widest point of chest
- Add 25mm to both measurements
- Cats prefer snug openings — don't oversize
- For multi-cat households measure the largest cat
Measuring for Dogs
- Measure height at the shoulder — varies widely by breed
- Measure width at chest or hips — whichever is wider
- Add 25mm to both measurements
- Dogs need more clearance than cats — err on the larger side
- For multi-dog households measure the largest dog
How to Use Your Measurements to Choose a Door
Once you have your height and width measurements (plus the 25mm addition), compare them against the flap opening dimensions listed on each product page. The flap opening must be equal to or larger than both your measurements.
The easiest way to do this is to use our interactive size guide — enter your pet's weight and we'll recommend the right model from the Catwalk® or Dogwalk® range automatically.
Use our free interactive size calculator to find the perfect pet door for your cat or dog in under 60 seconds. Find My Pet Door →
Measuring the Installation Location
As well as measuring your pet, you also need to confirm that your chosen installation location can accommodate the door. Key things to check:
- Glass thickness — Pet-Tek glass fitting models suit 3mm to 32mm panels
- Door panel thickness — wood fitting models suit 11mm to 52mm timber or PVC panels
- Clearance from frame — the cut-out centre should be at least 100mm from any frame edge
- Height from floor — centre of flap opening should be 15–20cm above ground for cats, higher for larger dogs
Quick Reference Size Guide
| Pet Type | Typical Weight | Approx Height | Approx Width | Recommended Range |
|---|---|---|---|---|
| Small cat | 2–4kg | 20–22cm | 14–16cm | Catwalk® Small |
| Average cat | 4–6kg | 23–27cm | 16–19cm | Catwalk® Medium |
| Large cat | 6–9kg | 27–32cm | 19–22cm | Catwalk® Large |
| Small dog | 4–8kg | 25–32cm | 18–22cm | Dogwalk® Small |
| Medium dog | 8–18kg | 32–45cm | 22–30cm | Dogwalk® Medium |
| Large dog | 18kg+ | 45cm+ | 30cm+ | Dogwalk® Large |
These are approximate guides only. Always verify against your pet's actual measurements and the flap opening dimensions listed on the product page. If your pet falls between sizes, always size up.
Frequently Asked Questions
Find the right door for your pet in 60 seconds
Use our free interactive size guide — enter your pet's weight and door type and we'll recommend the exact right model from the Catwalk® and Dogwalk® range.
Find My Pet Door →