How Big Should a Gerbil Cage Be? | Size That Works

Two gerbils need a cage with at least 20 gallons or 400 square inches of floor space, with 8–12 inches of bedding for burrowing.

Most pet stores sell enclosures that look big but fail gerbils on the one thing they need most: deep, solid floor space for digging. A 20-gallon tank or similarly sized enclosure with 400 square inches of floor space is the common minimum for a pair, and bigger always beats taller. Here’s what the numbers mean, why bedding depth matters as much as footprint, and how to pick the right setup the first time.

What Size Cage Do Two Gerbils Need?

Plan on at least a 20-gallon tank or about 400 square inches of floor space for a pair of gerbils. That’s the most common minimum across pet care guidance, and it gives two animals room to dig, sleep apart when they want, and keep their natural social structure without crowding.

One note on the range of advice out there: the Merck Veterinary Manual uses a more permissive rule of thumb of 5 gallons per gerbil, so 10 gallons for two. That’s a looser standard than the 20-gallon-for-a-pair guidance most hobbyist and rescue groups use, and it’s safer to treat it as the absolute floor, not a comfortable target. Better-than-minimum recommendations often point to a 40-gallon breeder tank or larger for a pair, mainly because it supports deep bedding and real tunneling behavior.

Why Bedding Depth Matters More Than Height

Gerbils are burrowing animals, and floor space with deep substrate matters more than vertical levels. The RSPCA recommends 20–30 cm of bedding (about 8–12 inches) and says the gerbilarium should ideally be around 50 cm high so the animals can dig deeply and still stand upright on their hind legs.

That depth requirement is exactly why tall wire cages are a poor fit as the main home. A wire cage with multiple levels looks generous, but if it can’t hold deep substrate on a solid floor, your gerbils lose the one behavior they’re built for. Use wire components as a topper or upper section if you like, but the main living space needs a solid floor that holds tunnels.

The same logic explains why 12 inches of height is the common minimum: the animals need room above the bedding to move and stand normally.

Official Welfare Standards and What They Actually Say

The strongest official figures come from UK-based bodies, and they’re useful benchmarks even for US pet owners. The RSPCA recommends a gerbilarium with solid glass walls, a secure wire-mesh top, and a solid floor, with 20–30 cm of bedding.

The numbers vary because different bodies weigh different factors, but the pattern is consistent: give more floor space than you think you need, keep the bedding deep, and prioritize burrowing room over climbing space.

If you’re deciding between tanks, a 20-gallon is the entry point but a roundup of the best cages for gerbils can help you spot models that actually support deep substrate and solid floors.

Environment Beyond the Cage Size

Size gets the attention, but the environment inside matters just as much. Keep the enclosure at roughly 20–24°C with 35–50% humidity, ensure good ventilation and a light-dark cycle, and provide a solid floor covered with 20–30 cm of substrate.

Gerbils are social animals, so most guidance assumes pairs or groups rather than single housing. More floor space is better than more vertical levels every time, because a gerbil’s natural tunneling behavior depends on a deep, solid-floored area. If your cage can’t hold at least 8 inches of bedding, it’s too small regardless of its gallon rating.