Small pet housing

Small pet housing is governed by published figures that differ enormously by species, and the single most useful thing anyone can do before buying is look up the number for their animal. A hamster needs 100 x 50cm of continuous floor and 25cm of bedding, on PDSA's figures. A pair of guinea pigs needs 7.5 square feet minimum and 10.5 preferred, on Humane World for Animals'. A pair of rabbits needs 3m x 2m x 1m, which RWAF and the RSPCA publish independently and which is twelve times the hamster figure. Rats need half-inch bar spacing and a solid floor; ferrets need the same half inch; chinchillas need height and no galvanized wire. This page puts every figure this site uses in one table, with its issuer, and it records the places where a well-known body publishes no figure at all rather than quietly supplying one.

Almost everything that goes wrong in small-pet housing goes wrong at the point of purchase, and it goes wrong because the buyer had no number in their head. Pet-store enclosures are sized to shelf space and price points, and nothing on a box tells you the published minimum for the animal it has a picture of. So this is a reference page rather than an argument: here are the numbers, here is who issued them, and here is what to do with them.

Floor area, by species

Where the sources disagree, and what we do about it

Two of the rows above contradict each other, and that is the most useful thing on this page. For ferrets, VCA suggests four square feet and PDSA publishes 10 square meters per pair — about 107 square feet. For rats, the MSPCA suggests a 24-inch cube and a peer-reviewed expert consultation says nothing under roughly 35 to 47 inches in height and width is suitable.

Our policy is to print both and explain the difference rather than pick. The ferret gap is explained by what each figure describes: VCA's is a cage for an animal that is out of it for two to three hours a day minimum, PDSA's is the space ferrets live in. The rat gap is a difference of source type — a shelter's practical guidance against an academic expert panel working from body length. How we test sets out the method, and the standing rule is that we never average two published figures into a third.

Bedding depth, where it is published

Depth is the figure that decides enclosure format, not just enclosure size. Ten inches of substrate cannot be held by a wire cage — it spills through the bars at a quarter of that depth — which is why both the hamster and gerbil guidance pushes towards solid-walled enclosures and why Woodgreen advises against wire cages for gerbils outright.

Bar spacing and flooring

• Rats: 1/2 inch, on the MSPCA's figure, with a solid bottom and no wire mesh platforms, which it says can cause abrasions to feet. The RSPCA asks for bar spacing small enough to stop a rat poking its head through.
• Ferrets: 1/2 inch in practice. VCA publishes no spacing figure, but one inch will not hold a kit, and the MSD Veterinary Manual asks you to check for any openings large enough for the ferret to escape.
• Guinea pigs: wire floors are not acceptable, stated by Humane World for Animals alongside plastic tubs and glass aquariums.
• Chinchillas: no galvanized wire, because VCA states the zinc it contains is toxic if ingested, and at least part of a wire floor should be covered with solid material.
• Hamsters: the RSPCA publishes no spacing figure and prefers mesh sides to solid ones, which is a position we print and partly disagree with — see hamster cage ventilation.
• Rabbits: wire floors are a material problem rather than a published rule-out. Rabbit hutch flooring covers it.

Height and temperature

What nobody publishes

The gaps are as useful as the figures, because they tell you when a number you have been quoted is somebody's invention. The RSPCA publishes no numeric floor area for hamsters at all — its hamster guidance is entirely qualitative — so any square-inch minimum attributed to the RSPCA is an attribution to a figure it does not publish. PDSA publishes no gerbil enclosure figure, asking only for one as large as possible. The RSPCA publishes no rat cage size, asking only that it be as large as possible. No source we read publishes a ferret jump height, a per-ferret floor allowance, or a ventilation specification in square inches of open mesh.

Recording those absences is the point of the standards hub. It is also the reason this site will sometimes tell you that a widely repeated number has no issuer behind it.

How to use these figures when you shop

1. 1.Find your animal's row and write the floor area down before you look at a single product.
2. 2.Ignore the stated living space on the box. Measure the longest unbroken length by the widest unbroken width of the base and multiply. Tube volume, upper levels and attached tunnels are not floor.
3. 3.Check the depth figure if your animal burrows. If the enclosure cannot hold ten inches of substrate, it will not meet the hamster or gerbil guidance regardless of its footprint.
4. 4.Check bar spacing against the animal you have, not the species average. A kit or a juvenile gets through gaps an adult cannot.
5. 5.Check the floor. Wire is ruled out or warned against for every species here that has guidance on it.
6. 6.Budget for the furniture inside the figure, not on top of it. Hides, hay, water and a wheel all stand on the floor you just measured.

If you want the shortlist rather than the reference, the best small animal cages attaches one product to each of these figures, and the best small pets works the question from the other end — which animal suits the space and the household you actually have.