Cat Litter Box Size Calculator
Use our Cat Litter Box Size Calculator to find the right litter tray size for your cat.
Do not include the tail. This is the measurement used for the standard 1.5x sizing rule.
Your recommended litter box size
Minimum interior length
27.0 in
Ideal interior width
22.0 in
Recommended external length
27.0 in
Recommended external width
22.0 in
Suggested box size category: Large
Suggested entry height: about 5.0 in
Suggested litter depth: 3–4 inches
Suggested number of boxes in the home: 2
Quick interpretation
- • If your current tray is shorter than the minimum interior length above, it is probably too small.
- • Large breeds often need jumbo or XL trays, not standard retail boxes.
- • Covered and top-entry boxes usually need to be sized up.
- • Senior cats often need a lower entry, even if the box itself is large.
Why litter box size matters
A litter box is not just a tray of litter. It is part of your cat’s routine, territory, and sense of safety. If the box is too small, your cat may struggle to turn, dig, choose a toileting spot, and bury waste comfortably.
A cramped litter box can contribute to accidents just outside the tray, messy elimination on the edge of the box, stress-based avoidance, and more difficulty spotting changes in urine or stool that may indicate health problems.
How big should a cat litter box be?
A strong rule of thumb is that the litter box should be at least 1.5 times your cat’s body length, measured from the nose to the base of the tail.
• A 16-inch cat needs a box around 24 inches long.
• An 18-inch cat needs a box around 27 inches long.
• Large breeds often need boxes in the 30–35 inch range.
How to measure your cat correctly
- Wait until your cat is standing naturally.
- Measure from the tip of the nose to the base of the tail.
- Do not include the full tail length.
- Multiply that body length by 1.5 to get the minimum tray length.
- Add extra width so your cat has room to turn and dig comfortably.
Covered vs open litter boxes
Open boxes usually provide the full usable floor space and better ventilation. Covered and top-entry boxes often look bigger than they really are because the interior space is reduced by the hood or shape of the shell.
Open boxes
- • Better ventilation
- • Easier to monitor urine and stool
- • Usually less stressful for many cats
- • Better for seniors and mobility-limited cats
Covered or top-entry boxes
- • Less usable interior space
- • Can trap odours
- • May feel more enclosed or stressful
- • Usually need sizing up
Best litter box size by life stage
Kittens
Kittens need easy access, so lower sides matter. They may start with smaller trays, but once growth picks up, it is worth moving them into a properly sized adult box early.
Adult cats
Adult cats usually need a large rectangular box with enough room to turn, dig, eliminate, and bury without touching the edges.
Senior cats
Senior cats still need space, but they often benefit from lower entry heights and more straightforward access. A large open box is often the safest option.
How many litter boxes should you have?
Size matters, but quantity matters too. A common guideline is one litter box per cat, plus one extra.
• 1 cat = 2 boxes
• 2 cats = 3 boxes
• 3 cats = 4 boxes
This helps reduce territorial tension, gives each cat more choice, and lowers the chance of litter box avoidance.
Best litter box types for large cats
Many standard commercial litter trays are too small for big cats. If your cat is long-bodied or heavy, it is often better to look at jumbo trays, under-bed storage totes, or large utility tubs rather than standard pet shop boxes.
The most practical option for many homes is a large rectangular open box with enough length for stretching and enough width for easy turning.
Where to place a larger litter box
Even the right size box can fail if it is in the wrong place. Aim for a location that feels quiet, easy to access, and away from food and water.
Better locations
- • Quiet corners
- • Low-traffic rooms
- • Easy-access spaces
- • One box on each floor in larger homes
Locations to avoid
- • Near loud appliances
- • Tight cupboards or dark cupboards
- • Right beside food and water
- • Areas where doors may trap the cat
Quick checklist before you buy a litter box
- • Check the interior measurements, not just the outer shell
- • Make sure the box is at least 1.5x your cat’s body length
- • Size up if the box is covered or top-entry
- • Choose lower entry sides for kittens and seniors
- • Use the one-box-per-cat-plus-one rule for multi-cat homes
- • Make sure there is enough room to scoop and clean the box properly
Frequently Asked Questions
How big should a cat litter box be?
A good rule is that the litter box should be at least 1.5 times your cat’s body length, measured from nose to the base of the tail.
Should I measure my cat including the tail?
No. Measure from the tip of the nose to the base of the tail. Do not include the full tail length.
Are covered litter boxes smaller inside?
Yes. Covered and top-entry boxes often have less usable interior space than their external measurements suggest, so you usually need to size up.
How many litter boxes should I have for multiple cats?
A common rule is one litter box per cat, plus one extra. So if you have two cats, aim for three litter boxes.
What size litter box is best for a large cat?
Large cats often need jumbo or XL boxes, and many standard retail litter trays are too small once you compare them to the 1.5x body-length rule.
What kind of litter box is best for senior cats?
Senior cats usually do best with a large open litter box that has a lower entry height for easier access.
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