How we test
We buy every litter, test it against five fixed criteria under identical conditions, and score each out of five. Wherever we can, an instrument decides rather than an opinion: a scale, a filter, a gas meter, a sieve. This page is the whole method, so you can see how any score was reached.
Dust
The fine particles a litter releases into the air on pouring and scooping, and the film they leave around the box.
Less dust in the air you and your cat breathe.
What we want
Litter you can pour without clouding the room or the air your cat breathes from a few inches away. It matters for asthma-prone homes, so we score it strictly. We report what we measure and never diagnose.
How we test it
We measure dust by weight, not by eye. A fixed volume of litter drops inside a sealed chamber while a fan draws the air through a filter we weigh before and after. The gain in milligrams is the dust released. A laser particle counter logs airborne particles once they settle. Three runs, averaged.
The scale
| Score | Means | On the list |
|---|---|---|
| 5 | Negligible dust by weight; no particle rise. | 10 |
| 4 | A trace on the filter; clears at once. | 28 |
| 3 | Light, measurable dust; settles in seconds. | 10 |
| 2 | A clear rise on the filter; visible haze. | 2 |
| 1 | Heavy by weight; hangs in the air. | – |
| 0 | Extreme; a concern for sensitive homes. | – |
Half-point scores are counted with the whole number below them.
Clumping
Whether liquid sets into a firm clump that lifts out in one piece, and how strongly that clump holds together.
Firm clumps that lift out in one scoop.
What we want
A clean single lift that keeps the box usable between changes. Litter that crumbles forces you to empty the whole box far more often than the price suggests.
How we test it
We pour 10 ml of a standard saline solution, a consistent stand-in for urine, onto a level bed of litter. After it sets we lift the clump onto a sieve, shake it for a few seconds, and weigh what stays together. The share retained is the clump strength, and we look for above 90%.
We also record absorption capacity, the grams of liquid held per gram of litter. Litter that does not clump is scored on how completely it absorbs and locks the same dose, and labelled as such.
The scale
| Score | Means | On the list |
|---|---|---|
| 5 | Over 95% retained; lifts intact; absorbs fast. | 9 |
| 4 | Around 90% retained; only a trace of crumb. | 36 |
| 3 | Holds if lifted with care; some crumb or stick. | 5 |
| 2 | Fragile; falls below useful retention. | – |
| 1 | Breaks apart; cements to the box; mushy. | – |
| 0 | No usable clump forms. | – |
Half-point scores are counted with the whole number below them.
Odour
How well the litter holds back the ammonia and sulphur compounds that make a used box smell, and how long it keeps doing it.
A box that stays fresh for days, not hours.
What we want
A box that stays clean to the air for days, even with several cats. Perfume that hides a smell without controlling it is not odour control, and the gas reading exposes it.
How we test it
We measure odour as a gas, not by nose. A fixed amount of litter goes into a sealed vessel and is dosed with a standard ammonia and urine source. We then read the headspace ammonia in parts per million with a gas meter at set points through 72 hours. A small blind panel adds a sense check, but the ammonia figure drives the score.
The scale
| Score | Means | On the list |
|---|---|---|
| 5 | Headspace ammonia near zero at 72 hours. | 11 |
| 4 | Very low through 72 hours. | 29 |
| 3 | Climbs by around 48 hours, or leans on perfume. | 10 |
| 2 | Rises within a day. | – |
| 1 | High ammonia by 24 hours, or pure masking. | – |
| 0 | No real control. | – |
Half-point scores are counted with the whole number below them.
Tracking
How much litter leaves the box on paws or over the side, and ends up across the floor.
Less litter on your floors and in your bed.
What we want
Litter that stays where it belongs. It is closely tied to grain size, since larger, denser granules travel less.
How we test it
We run a weighted contact pad over the litter to mimic a cat leaving the box, then collect and weigh every granule that crosses marked lines on the floor. Less weight scores higher.
We also measure mean grain size with a calliper and sieve, the physical driver of tracking. A real mat by the box with our own cats checks the bench figure against daily life, and we disclose it.
The scale
| Score | Means | On the list |
|---|---|---|
| 5 | Almost no weight escapes; nothing clings to paws. | 5 |
| 4 | A few stray grains nearby. | 29 |
| 3 | A modest scatter; some pickup on paws. | 16 |
| 2 | A steady trail past the box. | – |
| 1 | Heavy scatter; clings to paws and bedding. | – |
| 0 | Tracks through the house. | – |
Half-point scores are counted with the whole number below them.
Sustainability
The environmental footprint of the litter: its material, its disposal, its packaging, and whether the eco claims hold up.
A litter that is kinder to the planet.
What we want
To reward genuinely lower-impact litters and to refuse greenwashing. This one is an evidence checklist against named standards, not a bench test, and we say so.
How we score it
Material. Renewable, biodegradable plant material (tofu, cassava, recycled paper) rates highest. Sodium bentonite clay, strip-mined and neither renewable nor biodegradable, rates lowest. Silica sits between.
Certification. We look for real compost certification (ASTM D6400 or D6868, or EN 13432), not a vague “natural” label.
Disposal claims. We treat “flushable” and “septic safe” claims with scrutiny. Independent testing (NSF/ANSI 350 and NSF 46) shows most fail, and we never tell you to flush cat waste, which also carries a parasite risk.
Packaging. Recyclable or recycled content beats single-use plastic.
The scale
| Score | Means | On the list |
|---|---|---|
| 5 | Renewable, certified compostable; recyclable pack; claims verified. | 6 |
| 4 | Mostly renewable and recyclable; small footprint. | 17 |
| 3 | Partly renewable; moderate footprint; claims hold up. | 10 |
| 2 | Mostly clay or heavy on plastic, little to offset it. | 17 |
| 1 | Strip-mined clay, landfill only, or claims that fail testing. | – |
| 0 | High impact and misleading about it. | – |
Half-point scores are counted with the whole number below them.
How we keep it fair
- We buy what we test.
- Free samples are disclosed and do not move the score.
- Fixed and repeatable.
- Same instruments, doses and conditions, three runs averaged.
- Fact, not opinion.
- Scores come from what we measured; judgement calls are flagged as ours.
- No paid placement.
- Strip the commercial links out and the ranking is identical.