Quick answer: What size litter box does your cat need? As a general rule, pick a box at least 1.5 times as long as your cat, measured from nose to the base of the tail, and about as wide as your cat is long. For a cat that measures 18 inches, that means a box around 27 inches long.
This guide is for anyone buying a first litter box, replacing one that seems cramped, or wondering whether a big cat will fit in an enclosed or automatic litter box. It covers the sizing rule, a size chart, how to measure your cat, signs a box is too small, and what changes for large cats, kittens, senior cats and self-cleaning models.
Key takeaways
- A good litter box is at least 1.5 times your cat's length from nose to the base of the tail.
- Many standard litter pans are shorter than that rule suggests for an average adult cat, so "large" on the label does not guarantee a good fit.
- Entry height matters as much as floor space for kittens, senior cats and cats with stiff joints.
- For an enclosed or automatic litter box, check the maker's weight range and the opening, not just the outside dimensions.
- If your cat suddenly stops using a box that used to fit, ask your vet before assuming size is the cause.
What size litter box does a cat need?
A cat needs a litter box at least 1.5 times its body length, with a width roughly equal to its body length. Body length here means nose to the base of the tail, not including the tail itself. This is a widely used rule of thumb, not an exact standard, and it gives a cat room to turn around, dig and cover without standing on the edge.
The chart below simply applies the rule to different cat lengths.
| Cat length (nose to base of tail) | Minimum box length (1.5x) | Minimum box width |
|---|---|---|
| 12 inches (kitten or very small cat) | 18 inches | 12 inches |
| 14 inches | 21 inches | 14 inches |
| 16 inches | 24 inches | 16 inches |
| 18 inches | 27 inches | 18 inches |
| 20 inches | 30 inches | 20 inches |
| 22 inches (large breed) | 33 inches | 22 inches |
Treat these as targets for an open pan. If the ideal size will not fit in your home, get as close as you can and keep the box very clean.
How do you measure your cat for a litter box?
You measure a cat for a litter box by taking its length from the tip of the nose to the base of the tail, then multiplying by 1.5. All you need is a soft tape measure.
- Wait until your cat is standing or stretched out calmly, for example while eating.
- Measure from the tip of the nose to the base of the tail, where the tail meets the body. Leave the tail out.
- Multiply that number by 1.5 to get the minimum box length.
- Use the cat's length itself as the minimum box width.
- Compare both numbers with the inside dimensions of the box, since thick walls and rims reduce usable space.
If your cat is still growing, size the box for the adult you expect, or plan to move up a size later.
How do you know if a litter box is too small?
A litter box is probably too small if your cat cannot turn around inside it without touching the sides or stepping on the rim. Other common signs include:
- Your cat perches with paws on the edge instead of standing in the litter.
- Urine or stool regularly lands over the side even though your cat is clearly trying to use the box.
- Your cat digs at the walls or the floor outside the box instead of the litter.
A cramped box is only one of several reasons a cat may avoid it. Our guide to why a cat stops using the litter box covers the others. If the change is sudden, or you notice straining, frequent trips or accidents around the house, ask your vet, because those can point to a health problem instead of a sizing problem.
What litter box size do large cats need?
Large cats need a litter box that is longer and wider than most standard pans, usually 30 inches or more for a cat around 20 inches long. Heavier cats also need a sturdy base that does not tip when they step on the edge.
When you shop for a big cat, check three things: the inside length and width, the weight the box is built for, and the size of the entry. If you are considering an enclosed model, our automatic litter box for large cats page explains what to look for. Be honest about the fit: a very long or very heavy cat is often happiest in an extra-large open pan.
Does entry height matter as much as litter box dimensions?
Yes, entry height matters as much as litter box dimensions for kittens, older cats and any cat with limited mobility. A box can have plenty of floor space and still be hard to use if the cat has to climb or jump to get in.
Kittens
Kittens need a low entry they can step over, usually only a few inches high. Floor space matters less at this age.
Senior cats and cats with stiff joints
Older cats often do best with a low, wide entry and a stable floor. If your cat hesitates at the entry or has started going beside the box, talk to your vet, and see our guide to what senior cats need from a litter box.
Side height and litter depth
Tall sides help with cats that dig hard or spray urine high, as long as one side stays low enough to enter. Remember that litter takes up space too: most cats do well with an even layer of 2 to 3 inches, as explained in our guide to how much litter to put in a litter box.
How do you size an automatic litter box?
You size an automatic litter box by checking the maker's weight range, the opening, and the outside footprint, because the 1.5x rule for open pans does not translate directly to an enclosed drum. A self-cleaning litter box removes waste after each visit, so the litter stays clean, but its flat floor area is usually smaller than a jumbo open pan.
As one example, the LitterLux Self-Cleaning Litter Box has a 65L drum and is designed for cats weighing 1 to 8 kg, which is about 2.2 to 17.6 lb, and for homes with up to 2 cats. Its outside dimensions are 22.8 inches deep, 20.4 inches wide and 21.4 inches high. You can see the full measurements on the tech specs page.
That will suit many adult cats, but not every cat. If your cat weighs more than 17.6 lb, is under 2.2 lb, or strongly prefers to stretch out fully while digging, a large open pan is the better choice. If your cat is inside the range, you can compare options on our self-cleaning litter box page.
How much floor space does a litter box need?
A litter box needs its own footprint plus clear space in front for your cat to walk in and out, and enough room for you to scoop or empty it. Measure the spot before you buy, including any shelf or counter above an enclosed box.
A box that fits your cat but sits in a tight, noisy corner may still go unused. For help, read our guide to the best and worst places to put a litter box.
Frequently asked questions
Can a litter box be too big for a cat?
A litter box is very rarely too big for a healthy adult cat. Extra floor space gives a cat more room to turn, dig and choose a clean spot. The real limits are your floor space and the entry height, since tall sides can be hard for a kitten or a senior cat to climb over.
How big should a litter box be for a kitten?
A kitten needs a litter box that is easy to climb into more than one that is large. Look for an entry only a few inches high and enough room to turn around. Because kittens grow quickly, many owners start with a full-size box that has one low side.
How big should a litter box be for two cats?
Size each litter box for your largest cat, using the 1.5 times body length rule. One bigger box does not replace a second box, because the common guideline is one box per cat plus one extra, placed in different spots. If two cats share a single box, it needs cleaning much more often.
How tall should the sides of a litter box be?
The sides of a litter box should be tall enough to hold the litter in but low enough at the entry for your cat to step over easily. Cats that dig hard or spray urine high usually do better with tall sides or an enclosed box, while kittens and senior cats usually need an entry only a few inches high.
Will a large cat fit in an automatic litter box?
A large cat will fit in an automatic litter box only if the cat is inside the maker's stated weight range and can turn around comfortably inside. Check the weight limit and the size of the opening before you buy. Cats above the limit are usually better served by an extra-large open box.
The bottom line
If you are still asking what size litter box to buy, start with the 1.5x rule: measure your cat from nose to the base of the tail and choose a box at least one and a half times that length. Then check the entry height for your cat's age and mobility, and for any enclosed or automatic model, confirm your cat is inside the stated weight range. If your cat fits the 2.2 to 17.6 lb range and you would like a box that cleans itself after every visit, take a look at the LitterLux Self-Cleaning Litter Box.
