Gerbil cage size: how big it really needs to be

How big of a cage do you need for a gerbil?

For the usual pair, at least 100 × 50 × 50 cm (39 × 20 × 20 in). That is Wood Green's minimum for two gerbils and the European welfare standard quoted by Gerbil Care UK. Gerbils should never live alone, so there is no real size for one gerbil: plan for two from the start.

Why so big? Gerbils are burrowers. The RSPCA says wild gerbils dig tunnels as deep as 1.7 m (5.5 ft) and as long as 6 to 8 m (20 to 26 ft). A tank has to give them room to dig, nest, store food, run and get away from each other. In a small cage they often dig in one corner over and over, which the RSPCA describes as a sign of stress, and the fix it suggests is more enrichment or a deeper home.

Gerbil cage size by number of gerbils

Guidance varies a little between countries. This table shows the main figures side by side.

Older guidance is much smaller. The MSD Veterinary Manual's owner pages give 5 gallons per gerbil and a 10-gallon tank for two, and PetMD says at least 20 gallons for a pair. Those sizes cannot hold 25 cm (10 in) of bedding plus a wheel and sand bath, so we follow Wood Green and the European standard instead, and treat the US 40-gallon figure as the bare minimum.

What size tank do I need for 2 gerbils?

A tank of 100 × 50 × 50 cm (39 × 20 × 20 in), or in US sizes a 40-gallon tank at the least. Oregon Humane Society and the BC SPCA both give 40 gallons as the minimum for two, and Oregon Humane adds that any wire cage should have at least 600 square inches (3,870 square cm) of floor with room for deep bedding.

A 40-gallon breeder tank, the common long, wide 40-gallon shape, is about 36 × 18 × 16 in (91 × 46 × 41 cm). That gives about 648 square inches (4,180 square cm) of floor, a little under the European figure. If you can fit something longer, do.

How tall should a gerbil tank be?

Tall enough for 25 cm (10 in) of bedding plus at least 12 cm (5 in) above it, so an adult can stand upright on top. The RSPCA suggests a gerbilarium around 50 cm (20 in) high and notes adults are about 12 cm (5 in) tall standing. Gerbil Care UK says the glass or clear part of the tank should be at least 40 cm (16 in) deep, because anything shallower can't hold enough bedding. That is the problem with many plastic-based cages: Gerbil Care UK rejects the Ferplast Karat 100, for example, because its base is only 25 cm (10 in) deep.

Biggest and large gerbil tanks that pass

These are tanks Gerbil Care UK has measured, from the minimum up to large. Sizes are length × width × height.

IKEA stopped selling the Detolf new in December 2023, Gerbil Care UK notes, but second-hand ones are easy to find and need a home-made mesh lid. The BC SPCA also suggests a used fish tank: it doesn't need to hold water, so a leak doesn't matter. Our picks of the best gerbil cages include where to buy.

Common cages that are too small

Gerbil Care UK measured many popular cages and rejects them for gerbils, including the Savic Gerbilarium at 52 × 51 cm (21 × 20 in), the Pets at Home Classic Premium at 78 × 48 cm (31 × 19 in) and the Little Friends Savoy at 59 × 38 cm (23 × 15 in). Most are sold as gerbil homes, so check the measurements, not the label.

Tank, cage or gerbilarium: which is best?

A glass tank with a mesh lid. The RSPCA recommends solid glass walls, a secure wire-mesh top and a solid floor, and advises against metal-bar cages because gerbils can slip and hurt their legs and feet, and gnawing bars damages teeth. Bars also let bedding fly out. Wood Green adds that a normal fish tank lid is not suitable: use a sturdy wooden frame with 1 × 1 cm (0.4 × 0.4 in) welded mesh.

• Glass or clear base at least 40 cm (16 in) deep
• Secure mesh lid or topper with small gaps
• No mesh shelves, which Wood Green warns can injure feet
• No solid shelves a gerbil can be trapped under
• No plastic within reach of teeth
• No separate boxes joined by tubes, which Gerbil Care UK says can make gerbils territorial

Once you have the tank, our gerbil cage setup guide shows how to lay it out and our gerbil bedding guide covers what to fill it with.

What is the average size of a gerbil?

An adult Mongolian gerbil is about 10 to 12 cm (4 to 4.7 in) long in the body, with a furry tail of 8 to 11 cm (3 to 4.3 in). The MSD Veterinary Manual gives adult weight as 50 to 90 g (2 to 3 oz). Standing up, the RSPCA puts an adult at about 12 cm (5 in) tall. That small body is why people underestimate the tank: the gerbil is small, but the burrows it wants to build are not.

Gerbil litter size and what it means for space

A gerbil litter is one to eight pups, according to the MSD Veterinary Manual, with three to seven being usual according to Bowmanville Veterinary Clinic. Pregnancy lasts about 24 days, pups wean at around three weeks, and the BC SPCA says they must be separated by sex by eight weeks old, before they start breeding. A female can have up to 12 litters a year.

If you do end up with a bigger group, size up using the table above, and read our guide to gerbil pairs, clans and split cages, because larger groups fall out more often. For everything else, see the complete gerbil care guide.