Skip to content
Design free

Free calculator

Catio size calculator

How big should a catio be? Two ways round: tell the catio size calculator how many cats you have and it gives the catio they need, or give it the space you have and it says how many cats it holds. Every answer opens in the designer at that size.

Catio for my cats

Open this catio in the designer

Cats for my space

Open this size in the designer

How much space a catio needs per cat

We use 21.5 sq ft of floor per cat as the green line, the 2 square meters Animal Welfare Victoria asks for. The Association of Shelter Veterinarians (2022) sets 18 sq ft per adult cat as the minimum for cats housed together, and 11 sq ft is the least it calls ideal for one cat; below that our check is red (Animal Welfare Victoria, ASV 2022).

CatsFloor at 21.5 sq ft eachAt 18 sq ft eachFreestanding we proposeLean-to we propose
121.5 sq ft18 sq ft6x4 ft, 24 sq ft6x4 ft, 24 sq ft
243 sq ft36 sq ft8x6 ft, 48 sq ft10x5 ft, 50 sq ft
364.5 sq ft54 sq ft10x8 ft, 80 sq ft12x6 ft, 72 sq ft
486 sq ft72 sq ft12x8 ft, 96 sq ft16x8 ft, 128 sq ft
5107.5 sq ft90 sq ft12x10 ft, 120 sq ft16x8 ft, 128 sq ft
6129 sq ft108 sq ft16x10 ft, 160 sq ft20x8 ft, 160 sq ft

Proposed sizes are the smallest standard size in our designer where every space and shelf check is green, with a solid roof for 30 psf of snow. A double-door airlock takes its 36 x 42 in floor out of the space per cat.

  • Height: Animal Welfare Victoria: at least 2 m (about 79 in) tall. Best Friends: build it tall enough for a person to stand in. Lower is amber, never red: a window box or a low catio is still a catio.
  • Shelves: Animal Welfare Victoria: at least two platforms at different heights per enclosure. The ASV: perches and hiding places in every enclosure. Murdoch University: step the shelves for older cats. Our default adds one more for each cat beyond the first.
  • Litter and water: AAHA and AAFP (2021): one litter box per cat plus one. Best Friends and Humane World for Animals: a sheltered box in the catio, or easy access back into the house; Victoria: away from food and bedding.
8'6'
The 8x6 catio for two cats from above: 48 sq ft, 24 per cat.

Once you know the size, the catio cost calculator prices it, the catio plans show the nine standard designs, and the guide to building a catio covers the build. For one or two cats and little room, a window box catio gives them outdoor time without a yard.

Questions people ask

A good size for a catio is at least 21.5 sq ft of floor per cat and about 79 in (2 m) of height, after Animal Welfare Victoria. For two cats that is 43 sq ft, so an 8x6 ft catio (48 sq ft) is the smallest walk-in we draw for them.

For 2 cats a catio should have at least 43 sq ft of floor at our green line, and never less than 22 sq ft. Our designer proposes 8x6 ft freestanding or 10x5 ft against the house, with at least three shelves.

Multiply 21.5 sq ft by the number of cats for the floor, then add a shelf per extra cat: 2 shelves at different heights, plus one for each cat after the first. Four cats need about 86 sq ft, which our designer meets with a 12x8 ft freestanding catio.

Aim for 79 in, about 2 m, at the low side, the height Animal Welfare Victoria asks for; Best Friends suggests a catio a person can stand in. Lower is fine for a window box or a small lean-to: our check turns amber, never red, because cats use the shelves rather than the full height.