Clumping clay
Two inches, level
Enough for urine to be caught and sealed before it touches the plastic, without burying the clumps so deep you cannot find them.
Filling the boxGuide - 7 min read
How Much Cat Litter to Put in the Box
Two inches, level, for clumping litter. Less for pellets and crystals. Most people pour three or four inches because it feels generous, and it costs them money while making the box worse to use. Depth is not absorbency.
By ReviewCatLitter Editorial TeamUpdated Aug 22, 2026
Quick answer
- 1Two inches of clumping litter, levelled. That is the whole answer for most boxes.
- 2The ASPCA and Cornell both land on one to two inches, and both say not three to four.
- 3Pellets and crystals go shallower. Follow the bag, because they are not meant to be piled up.
- 4Depth is not absorbency. A four-inch bed is twice the litter in the bin on the same day.
- 5Fill to two inches once, draw a line on the outside of the box, and top up to the line from then on.
Where the one to two inches comes from
This is not a preference we invented. ASPCA says most cats like a shallow bed and to provide one to two inches rather than three to four. Cornell Feline Health Center lands on the same range: most cats prefer unscented, finer-textured litter about one to two inches deep.
Two organisations that spend their days on litter box refusals both point at the same number. If your cat has started perching on the rim, depth is worth checking before you change brands.
Depth by material
Wood or paper pellets
Shallower, and follow the bag
Pellets break down where they land and are meant to fall through a sifting tray. Piling them up stops the sifting working, so pellet bags usually ask for less depth than clay. Read the bag rather than guessing.
Silica crystals
Whatever the bag is sized for
Crystal bags are usually sold as one box-worth. Absorbency lives inside each bead, so adding a second bag on top buys you nothing except beads your cat has to wade through.
Corn, walnut, tofu and other naturals
Two inches, level
These clump like clay but weigh less, so a deep bed shifts underfoot and gets kicked over the rim.
What the extra two inches costs
Going from a two-inch bed to a four-inch bed puts twice the litter in the box, and you still throw the whole lot away on the same schedule. Here is what a pound costs across the litters we have bought and weighed, cheapest first.
| Litter | Bag | Bag price | Per pound |
|---|---|---|---|
| Frisco by Chewy | 40 lbs | $13.00 | $0.33 |
| Arm & Hammer Super Scoop | 40 lbs | $13.99 | $0.35 |
| Purina Tidy Cats | 35 lbs | $15.49 | $0.44 |
| Arm & Hammer Clump & Seal | 38 lbs | $16.99 | $0.45 |
| Fresh Step Scented | 42 lbs | $18.99 | $0.45 |
| Feline Pine | 40 lbs | $19.99 | $0.50 |
| Dr. Elsey's Ultra | 40 lbs | $20.99 | $0.52 |
| Arm & Hammer HardBall | 38 lbs | $19.99 | $0.53 |
| Dr. Elsey's Cat Attract | 40 lbs | $26.99 | $0.67 |
| Boxiecat Premium | 40 lbs | $27.99 | $0.70 |
| Naturally Fresh Walnut | 26 lbs | $24.99 | $0.96 |
| Ökocat Paper Pellet | 20 lbs | $19.99 | $1.00 |
| World's Best Cat Litter | 28 lbs | $29.99 | $1.07 |
| Sustainably Yours | 26 lbs | $29.99 | $1.15 |
| Catalyst Soft Wood | 18 lbs | $27.99 | $1.56 |
| Tuft + Paw | 9 lbs | $29.00 | $3.22 |
| PrettyLitter | 6 lbs | $24.00 | $4.00 |
The spread runs from $0.33 a pound on Frisco by Chewy to $4.00 on PrettyLitter. Overfilling a box hurts most at the expensive end.
Questions people ask
How many inches of cat litter should be in the box?
One to two inches for most cats. The ASPCA is explicit about it: provide one to two inches rather than three to four. Cornell gives the same figure. Deeper is not more absorbent, it is just more litter in the way.
How many pounds of litter does a box take?
It depends on the box and the material, not on a fixed number. Fill to a level two inches, mark the outside of the box at that line with a marker, and top up to the line from then on.
Does a deeper bed stop the box smelling?
No. Smell comes from waste sitting in the box, so scooping frequency changes it and depth does not. A deeper bed hides clumps, which usually means they get missed.
Does my cat need more litter because it digs a lot?
A heavy digger needs a bigger box or a higher-sided one, not a deeper bed. Adding depth to a small box just moves more litter onto the floor.
Measure it once, then forget the ruler
- Fill the empty box to two inches and level it with your hand.
- Draw a line on the outside of the box, at the litter line, with a permanent marker.
- Top up to the line after every scoop. That is the whole system.
- When the line stops holding, because the bed looks grey right through, that is your cue for a full change rather than another top-up.
Additive
Purrify - the additive we use in our own homes
Activated carbon you add to the litter you already buy. We have used it in our own homes for years, and with dozens of friends and family. You can keep your existing base litter.
Read our Purrify guide to picking a litter for odor control.
- Activated carbon, sold in bags
- 5.0 Google rating
- Stocked in 40+ pet stores across Canada
ReviewCatLitter editorial team
Updated Aug 22, 2026
Bag weights, bag prices and cost per pound on this page are the ones recorded when we bought each litter for testing. Depth advice is sourced to the ASPCA and Cornell, linked above.