Practical guide · Sources checked 8 September 2026
“Large” is a reassuring word on a litter tray listing. Unfortunately, the cat cannot read it, and the tray does not get any bigger when you point it out.
Measure from the nose to the base of the tail
Battersea recommends a tray at least one and a half times the cat's nose-to-tail-base length, with space to stand, turn and dig. It also warns that a “large” label does not necessarily mean an adult cat will have enough room.
For a practical measurement, wait until your cat is standing normally and relaxed. Measure the straight distance from the tip of the nose to where the tail joins the body, keeping the tape beside the cat. Do not include the tail or wind the tape around the body. If the cat walks off, try later. The measurement does not become more useful because everyone is cross.
Multiply that length by 1.5. Treat the result as a starting check, not a complete fitting service: width, the shape of the base, the lid and ease of entry still matter.
A measuring example in centimetres
For a hypothetical cat measuring 40cm from nose to tail base, the calculation is 40 × 1.5 = 60cm. Start by looking for at least 60cm of useful tray length, then assess the other dimensions. This is an example, not a measurement of Goldfish.
Our practical approach is to apply the length check to the space the cat can use, rather than counting projecting handles or a broad rim. Ask the seller what a quoted measurement includes if the listing does not say.
Internal dimensions and external dimensions do different jobs
| Dimension | Use it to check |
|---|---|
| External length and width | Whether the box fits the available floor space. Add room for access and cleaning. |
| Usable internal length and width | The space available for standing, turning and digging. Check for tapered walls, rounded corners and an inset base. |
| Internal height with a lid | Headroom inside the covered box. External height may include a handle or other space the cat cannot use. |
| Entrance height and opening | What the cat has to step over, climb onto or pass through. |
A 60cm external dimension does not establish 60cm inside. Nor does a tray with one suitably long side automatically offer enough turning space. Look for an internal drawing or ask for the usable base measurements instead of trying to infer them from a lifestyle photograph.
For a covered box, assess the inside with the lid fitted. For a top-entry design, include the space needed above the opening. Our top-entry versus front-entry guide takes that comparison further.
Entry height matters as much as floor space
Cats Protection advises low-sided trays for older cats and those with mobility difficulties. A roomy toilet is of limited help if getting into it is the difficult part.
For kittens, Battersea suggests a low-entry starter tray, moving to a full-sized adult tray when they can get in easily. Recheck the fit as the kitten grows rather than assuming the first tray is a permanent purchase.
High sides may look useful for containing litter, but keep access separate from the mess problem. Our tracking guide starts by distinguishing scattered litter, carried grains and cleaning spills.
Is your current tray too small?
Start with its measurements and watch whether your cat has room to stand, turn and dig without obvious restriction. Check the entrance too. Those observations can help you assess the arrangement, but they do not identify the cause of a toileting problem.
If your cat suddenly starts toileting elsewhere, stops using the tray or seems uncomfortable, speak to your vet. Cats Protection recommends checking for medical causes of sudden changes. A bigger box is not a diagnosis.
Also check where the tray sits and the cleaning routine. Size is one part of the setup, not an explanation for everything that happens near it.
Five checks before you buy
- Write down the cat's nose-to-tail-base measurement. Calculate the 1.5-times starting length.
- Find the usable inside dimensions. If the listing only supplies outer measurements, ask before treating them as internal space.
- Check width, headroom and entry. A single length figure cannot answer all three questions.
- Measure the location with doors and lids open. Include the route in and out and room to lift the tray for cleaning.
- Check the exact variant. Product names, photographs and size options can refer to different versions.
We have lived with our Feandrea covered box for about two years, and it works with our bathroom arrangement. That does not establish the right dimensions for another cat. Read our Feandrea litterbox review for the product-specific experience and listing details, then compare the exact variant with your own measurements.
If you are planning the whole setup, return to the first-cat essentials checklist. The objective is a toilet your cat can comfortably use. A confident adjective on the packaging is optional.
Sources & further reading
Guidance checked 8 September 2026: Battersea's litter tray setup advice and Cats Protection's toileting advice. The worked calculation and measurement drawing are illustrative; the listing checks are our practical application.
Explore all litter and tray guides or read our editorial standards.