Litter boxes
Litter Box Ideas That Don't Smell
Smell is a design problem before it's a cleaning problem. Here is what to check before you buy another box.
By Joel Wood. Picks and specs last checked .
The complaint
“I scoop twice a day and the room still smells. Guests notice the second they walk in. I’ve tried three litters and a covered box and nothing works.”
That’s the most common litter complaint, and the second most common is the fix that made it worse: an enclosed cabinet or furniture-style box that looked good and turned into a smell chamber within a month.
The third is the mess. Litter on the floor within three feet of the box, tracked down the hall, in the bed.
Why it fails
Most of the smell has three sources, and none of them is fixed by scooping more.
- Porous plastic. Cheap boxes are soft plastic that scratches under claws. Every scratch holds urine. After a few months the box itself smells, no matter how clean it looks.
- Enclosure without airflow. A covered box, or a cabinet with a box inside, holds ammonia in a small volume. The cat walks into it, hates it, and starts going elsewhere. That’s when the smell moves to a corner you can’t find.
- Too small. A box built for a kitten forces an adult cat to squat at the edge. Urine hits the rim or the wall behind it, and the box looks clean while the floor doesn’t.
- Wrong litter for the box. Lightweight and crystal litters track. Clay clumps hold smell if they’re not removed within hours. The box design and the litter have to match, and the marketing never says which goes with which.
- One box, two cats. Cats won’t share a box the way people expect. When one cat is displaced, the smell shows up in a closet or behind a sofa.
The fix is a box that’s big enough, made of the right material, open enough to breathe, and multiplied by the number of cats. Only then does the litter choice matter. The Cove litter box is the shape we mean: an open tray with high sides, a low entry and a hard, smooth interior, though it still scatters and it’s tight for a cat over 18 lb.
What to look for
Check every one before you buy. This is the part the pin couldn't fit.
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Floor area at least 1.5× the cat's length
Cats dig and turn. A box they can't turn in gets used at the edge, and the mess lands outside it. Most "standard" boxes are too small for an adult cat.
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High sides with a low entry, or a top entry for a fit cat
Sides under 8 inches let litter and spray out. A low cut-out at the front keeps it usable for older cats.
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A smooth, non-porous interior
Scratched plastic holds urine. A box that's been scooped for a year has a smell built into the surface. Look for hard, smooth plastic or an enamel liner.
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No carbon filter that needs replacing, or a plan to replace it
Filters work for about a month. After that, a covered box is a box that traps smell. If you won't replace filters, buy an open box.
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Space for one box per cat, plus one
The rule everyone ignores. Two cats sharing one box means one of them is going somewhere else, and that's the smell you can't find.
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Replace a plastic box about every two years
The surface scratches, and scratches hold odor no matter how well you clean. A box that still looks clean can be the source of the smell. If it's stainless, this doesn't apply.
Where it goes and how it breathes
Not next to the washer or the furnace, because a box that bangs or roars mid-visit gets avoided. Not beside food and water. Not in a dead-end spot with one way out, since a nervous cat wants an exit. On a floor the cat actually uses, not the basement it never visits. If the box lives in a cabinet, it needs a vented back, two openings, a wipeable interior, and enough headroom for the cat to stand.
How big should a litter box be?
At least one and a half times your cat's length from nose to base of tail. For an average cat that's about 22 inches long inside; for a Maine Coon it's closer to 30. Most boxes sold as "large" are 18 to 20 inches. If the cat can't turn around without touching the sides, it's too small, whatever the label says.
Why do vets not recommend closed litter boxes?
A hood traps the smell inside the box, where the cat is, rather than in the room, where you are. Cats avoid boxes that smell, and a covered box also hides the early signs of a problem, like small clumps or blood, that you'd catch in an open tray. If you want a lid for the room's sake, choose one with a vented back and two openings.
What goes in the box
Most litter box complaints are litter complaints. Four things to check: unscented, because perfume covers odor for you and puts cats off the box; clumping, so you remove waste instead of stirring it; 2 to 3 inches deep, which is enough to clump and shallow enough to scoop; and a scoop with wide slats, because fine-slat scoops jam on anything that isn't hard clay. If you switch litters, do it over a week by mixing the new one in, a quarter at a time. Cats reject sudden changes, and they reject the box, not the litter.
The fixes
Products that pass, and where each one falls short
Every card below lists the product's known flaw. If we can't name one, we don't list it.
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Litter-Robot 4
Whisker · $600 and up
- Scoops after every use, so waste never sits long enough to smell
- Sealed waste drawer with a carbon filter holds a week for one cat
- App tells you when the drawer is full instead of your nose
Known flaw
The price of a small appliance, and about the size of one — it needs about three feet of clearance. The cycle is loud enough to startle a nervous cat, and very large cats sit near the weight limit for the sensor.
Link to Whisker coming soon
Cove Litter Box
Tuft + Paw · $100–250
- Smooth, non-porous interior, high sides with a low corner entry, and no carbon filter to replace.
- 16 inches wide, 26 long and 6.5 high, with a 14 by 20 inch litter area. The optional Shelter adds 8 inches of height.
- Scoop, dustpan and hand brush included, stored along the back.
Known flaw
It still scatters. Owners report cats kicking litter out on the way, and the usable litter area is 20 inches long, which is tight for a cat over about 18 lb. The Shelter cover isn't latched down, so a boisterous cat knocks it askew. The included scoop's holes are wide enough that small clumps drop through.
Really Great Cat Litter
Tuft + Paw · Under $100
- $29 for a 9.25 lb bag, about $3 a pound against a market average closer to $2.45. Made from soybean fiber left over from tofu production, plus calcium carbonate, corn starch and pea fiber.
- Clumps, very low dust, and the pellets are elongated so less sticks to paws. The rare litter that is both low-tracking and flushable.
- Flushable in the unscented and lavender bags only. The OdorStop blend contains sodium bentonite and is not flushable.
Known flaw
Odor control is the complaint that comes up most. It holds 4.1 out of 5 across roughly 1,160 ratings, and the negative reviews say the same thing: ammonia builds within a day or two even with daily scooping, and the tofu smell mixes with waste rather than masking it. The clumps go soft and stick to the scoop and to a wet box floor, so you need a wide-slat scoop and you will leave residue behind. The litter is dark, which makes clumps hard to spot. And it still tracks, just less than clay. If odor is your main problem, this is not the fix. The box and the scooping schedule are.
XL Litter Box
Modkat · $100–250
- Convertible between top-entry and front-entry, so it works for most cats
- Tall walls stop spray and kicked litter completely
- Looks like a plain cube — it disappears in a bathroom corner
Known flaw
Top-entry is hard on older or arthritic cats, and the reusable liner is a proprietary part you will be buying again. The lid traps smell if you skip a day of scooping.
Link to Modkat coming soon
Get the litter box checklist
The size rule, the side height and the one-box-per-cat math. We'll also email you when something in this category actually passes, which isn't often.