# How Many Litter Boxes Do I Need? Free n+1 Calculator

> How many litter boxes do you need? Free calculator using the vet-backed one-per-cat-plus-one rule, adjusted for floors, automatic boxes and box size for your…

- Source: https://selfcleaninglitterboxguide.com/tools/how-many-litter-boxes/
- Markdown version: https://selfcleaninglitterboxguide.com/tools/how-many-litter-boxes.md

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# How many litter boxes do I need?
Vets' rule of thumb is one box per cat plus one, in different spots. Tell us how many cats and floors you have, and whether you plan to use automatic boxes, and we'll work out the number, where to put them and how big they should be.

Cats
Floors your cats use
Automatic boxes you'll use
Longest cat, nose to tail base (in, optional)

 My cats don't get along (or one guards the box)

## Automatic boxes rated for several cats
If you're adding an automatic box to a multi-cat home, these have the highest published cat ratings.

- 1![Whisker Litter-Robot 5](https://selfcleaninglitterboxguide.com/_astro/whisker-litter-robot-5.JMut0Qu8_Z1BLhyu.webp)Up to 5 cats, 3–30 lb[Whisker Litter-Robot 5](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-5/)Rotating globe · 3–30 lb · up to 5 cats8.5**$$$**$PremiumPrice tier: Premium[Check price](https://www.amazon.com/dp/B0HN8C8TFM?tag=selfcleaninglitterboxguide.com-20)
- 2![Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/_astro/whisker-litter-robot-4.CZhanV3w_12M27U.webp)Up to 4 cats, 3–25 lb[Whisker Litter-Robot 4](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-4/)Rotating globe · 3–25 lb · up to 4 cats8.7**$$$**$PremiumPrice tier: Premium[Check price](https://www.amazon.com/dp/B0BH6MD3DJ?tag=selfcleaninglitterboxguide.com-20)
- 3![Whisker Litter-Robot EVO](https://selfcleaninglitterboxguide.com/_astro/whisker-litter-robot-evo.qVzR9iO0_sr869.webp)Up to 2 cats, compact[Whisker Litter-Robot EVO](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-evo/)Rotating globe · 3–19 lb · up to 2 cats8.6**$$$**$PremiumPrice tier: Premium[Check price](https://www.amazon.com/dp/B0G6GDC4VN?tag=selfcleaninglitterboxguide.com-20)
- 4![PetSafe ScoopFree Crystal Smart Self-Cleaning Litter Box](https://selfcleaninglitterboxguide.com/_astro/petsafe-scoopfree-crystal-smart.DQ62GmN3_G0CIT.webp)1–2 cats, crystal trays[PetSafe ScoopFree Crystal Smart Self-Cleaning Litter Box](https://selfcleaninglitterboxguide.com/litter-boxes/petsafe-scoopfree-crystal-smart/)Rake + crystal tray · not published · up to 2 cats8.0**$**$$$BudgetPrice tier: Budget[Check price](https://www.amazon.com/dp/B087C7K4CP?tag=selfcleaninglitterboxguide.com-20)
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## How the count works

- **Base rule: cats + 1.** The AAFP and ISFM's owner guide on house-soiling recommends one litter box for each cat plus one extra, in multiple locations. The MSD Veterinary Manual says at least one more box than the number of cats.
- **Floors.** MSD recommends a box on each floor of a multi-floor home. If you have more floors than the base count, the floor count wins.
- **Automatic boxes count as one each.** Each automatic box is one location. We don't let it stand in for two, because it can be occupied, paused or offline. Keep at least one manual box, especially while a cat is adjusting.
- **Cats that don't get along** need boxes in separate areas so one cat can't guard every option. We add one box and remind you to spread them out.
- **Size.** The AAFP guide says a box should be about 1.5 times the cat's length from nose to the base of the tail.

## A worked example
Two cats in a two-story house, planning one [Litter-Robot EVO](https://selfcleaninglitterboxguide.com/litter-boxes/whisker-litter-robot-evo/). The base rule gives three boxes, more than the two floors, so you need three. One is the EVO; the other two are manual boxes, at least one of them on the other floor. If your longest cat measures 18 in from nose to tail base, each manual box should be about 27 in long, which rules out most standard pans. The AAFP guide suggests storage containers or concrete mixing trays as alternatives.
More detail is in [how many litter boxes per cat](https://selfcleaninglitterboxguide.com/posts/how-many-litter-boxes-per-cat/), and our [best self-cleaning litter boxes for multiple cats](https://selfcleaninglitterboxguide.com/posts/best-self-cleaning-litter-box-for-multiple-cats/).

## Frequently asked questions

### How many litter boxes do I need for two cats?
Three. The AAFP and ISFM's guidance to cat owners is one litter box for each cat plus one extra, in different locations around the home, and the MSD Veterinary Manual gives the same rule. In a two-story home, put at least one on each floor.

### Does a self-cleaning litter box count as more than one box?
We count it as one. It stays cleaner between visits, which WIRED notes reduces the need for extra boxes, but it's still one location, it can be occupied, and it can break down or pause. Vets' guidance is about locations and choice, not just cleanliness.

### Can I put two litter boxes next to each other?
It doesn't help much. The AAFP's owner guide notes that cats treat boxes placed side by side as one large litter box. Put them in different rooms or areas.

### How big should a litter box be?
The AAFP's owner guide says a box should be about 1.5 times the cat's length from nose to the base of the tail, and that many commercial boxes are too small. Bigger is better.