40 Gallon Leopard Gecko Enclosure: The Recommended Setup

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A 40 gallon leopard gecko enclosure is a good adult setup. Its 36 by 18 inch floor gives the gecko room for a real temperature gradient. Leopard geckos (Eublepharis macularius) live on the ground, so floor area counts and height does not.

For the full range of housing options, see the leopard gecko housing guide. This page stays with one size.

Is a 40 Gallon Tank Good for a Leopard Gecko?

Yes, for one adult. The tank meets or exceeds the floor space and volume figures in three published care sheets. Merck also advises the largest enclosure possible.

The sources do not agree on one minimum. Here are their figures as published.

The inch conversions in the table are arithmetic, not source figures. The RSPCA and Liverpool figures are smaller than the RVC figure, and the 40 gallon breeder clears both. The RVC height shortfall is real but small, and the RVC states a minimum, not an ideal.

What a 40 Gallon Leopard Gecko Enclosure Measures

Aquarium makers list the 40 gallon breeder as 36 inches long, 18 inches deep and 16 inches tall. Those are the nominal trade dimensions rather than a measured spec for one model. They work out to about 91 by 46 by 41 cm, with roughly 648 square inches (0.42 m2) of floor.

Do not confuse it with the 40 gallon long, which is a different tank with a different footprint. Check the listed length and depth before you buy, because the gallon number does not give floor area. Makers vary slightly, so measure your tank.

Merck gives a general rule for terrestrial lizards: 0.2 m2 of floor per 0.1 m of total length. Animal Diversity Web puts adults at about 220 mm, so the rule works out to about 0.44 m2.

The 0.42 m2 floor sits right at that figure. The rule covers terrestrial lizards in general, and the figure is arithmetic, not a gecko specific recommendation.

Which Ages and Sizes Suit It

Adults suit it best. Hatchlings measure about 85 mm and adults about 220 mm, rarely up to 10 inches (Animal Diversity Web). By the same Merck rule, a hatchling needs only about 0.17 m2 of floor.

Hatchlings and juveniles can live in this tank. A large open floor can make food hard to find, though.

Common keeper practice is a smaller tank for the first months, then a move up. No authoritative source gives a juvenile minimum, so treat that timing as guidance.

One adult is the intended load. The RSPCA and Liverpool minimums are written for one gecko.

None of the care sheets reviewed here sets a minimum for a pair. Keep one gecko per tank unless a reptile veterinarian advises otherwise.

Glass, PVC or Front Opening

A standard 40 gallon breeder is glass with a top opening. Liverpool describes a glass horizontal vivarium as suitable.

Merck disagrees: glass insulates poorly and swings in temperature, so wood, plastic or fiberglass are “preferable” though costlier. The RVC also recommends wood or fiberglass.

Merck adds that visible glass may stress reptiles, and a covered glass top can severely restrict ventilation. If you use glass, cover the back and sides with an opaque panel. Do not cut ventilation to hold humidity, because Merck says that often leads to skin and respiratory disease.

A PVC or wooden enclosure of similar floor size should hold heat better and often has front opening doors. Front doors let you reach the gecko without lifting it from above. The trade is cost, so choose by floor area first and material second.

How to Set Up a 40 Gallon Leopard Gecko Enclosure

Think of the floor as two zones with a gradient between them. The RVC and RSPCA both call for hides at the warm and cool ends. Put the heat at one end only, as Merck advises.

A workable layout for the 36 inch length uses three hides:

• Warm hide at the heated end, placed over or beside the warmest floor spot.
• Cool hide at the opposite end, in the coolest part of the tank.
• Humid hide in the middle or toward the warm side, holding damp moss or a damp paper towel.

Three hides is a common keeper layout. The sourced part is hides at both ends plus a humid hide.

The RVC, RSPCA and Liverpool all describe one to help shedding. The RSPCA suggests damp moss on a waterproof base, sprayed every few days.

Add clutter between the hides so the gecko can cross the tank under cover. The RSPCA suggests low, sturdy branches or rocks.

Keep them stable. Merck also lists a water bowl large enough to bathe in, so add a shallow dish.

For flooring, the sheets agree that paper towel is the simplest safe choice for short term use. The RVC and Liverpool warn that loose sand and wood chip can cause blockages if swallowed. The details are in the leopard gecko substrate guide.

Hide design and sizing are covered in the leopard gecko hides guide. Feed away from loose substrate, as the RVC advises, using a dish or a bare patch of floor.

Heating Plan for the Tank

The sources give different warm end figures, so set your target within their overlap and then measure. Quote each as published:

Fahrenheit values are conversions. A cool end near 24 to 26 C and a warm surface near 28 to 32 C fits most of these sheets.

Check both ends daily with a digital or infrared thermometer. The RSPCA notes that thermostats can be inaccurate.

Two heating styles fit this tank. An under tank mat gives belly warmth, which the RSPCA says leopard geckos absorb.

The RSPCA sets a mat to 30 C on an on/off thermostat, probe directly over the mat. Look for a thermostat with a probe.

An overhead ceramic heat emitter or basking lamp is the alternative. The RSPCA recommends a guarded 60 to 100 W ceramic or basking lamp, with a dimming thermostat probe above the substrate.

A mat is the simpler option here. An under tank heat mat covering part of one end gives the gradient.

Every heat source needs a thermostat and a guard. Merck links burns to unscreened lights and other heat sources, and advises against hot rocks.

Ordinary light bulbs cannot supply night heat. More detail is in the heating and lighting guide.

Optional UVB in a 40 Gallon Tank

UVB is optional, but one study supports it. In 18 leopard gecko hatchlings (Oonincx and colleagues, 2020), UVB for 2 hours a day gave blood vitamin D3 of 61 nmol/L against 38 nmol/L without it.

Both groups also received dietary D3. Neither showed bone disease or a growth difference over six months, and long term benefit is unknown.

Published guidance exists for keepers who add it. The RSPCA suggests a 2 to 5 percent tube over the hot end, covering one half to one third of the length.

It gives a UV index of 0.7 in the basking area, falling to zero in shade. The RVC mentions a low output tube on about 12 hours a day.

Merck says glass and plastic filter UVB, and tubes should sit within about 30 cm (12 inches) of the animal. That is easy in a 16 inch tall tank.

Look for a low output UVB tube. Merck gives 9 to 12 months for fluorescent tubes in general.

Humidity and Shedding

Leopard geckos come from dry and semi dry deserts and arid grasslands, according to Animal Diversity Web. Merck gives 20 to 30 percent humidity in a table row it shares with the bearded dragon, rising during a shed. The RVC and RSPCA give 30 to 40 percent, so the sources disagree by about 10 points.

Place a hygrometer in the middle of the tank, as the RVC advises. If readings run high, the RSPCA says increase ventilation. Merck lists low humidity among the causes of retained shed.

It says high humidity microclimates are often critical for arid species including leopard geckos. That is the job of the humid hide.

When to Upgrade Beyond 40 Gallons

A 40 gallon breeder is not a ceiling. Merck and the RSPCA both say to give the largest enclosure possible. Size up for a longer gradient or more clutter.

Upgrade also if the gecko cannot find both temperature zones, or the tank is crowded with gear. No source gives a size at which a 40 gallon breeder becomes too small for one adult. Judge by the animal: it should be able to move freely between hides, feed, drink and shed without crowding.

For husbandry beyond the tank, see the leopard gecko care guide.

The leopard gecko species overview covers the animal itself. Clean tank gear outside the kitchen. The CDC notes reptiles often carry Salmonella while healthy.

Frequently Asked Questions

Can two geckos share a 40 gallon leopard gecko enclosure?

None of the care sheets reviewed here sets a minimum for a pair. Their size figures are written for a single adult, so one gecko per tank is the safe default. Ask a reptile veterinarian before housing two together.

Do I need a tall tank for a leopard gecko?

Not much. The RSPCA minimum is 40 cm (about 16 inches) high and the RVC minimum is 18 inches. Leopard geckos are terrestrial, so floor area and length for the gradient matter more than height.

Should the tank be glass or PVC?

Both appear in the sources. Liverpool accepts glass, while Merck and the RVC prefer wood, plastic or fiberglass because glass loses heat. Whichever you choose, keep ventilation open and every heater thermostat controlled.

Does a 40 gallon breeder need a lid?

A secure, ventilated top is standard practice for a tank with an open top. Merck warns that a covered glass top can restrict ventilation. Keep most of the top open to air.

How do I clean a 40 gallon tank?

Merck says soap and water are generally all that is required, and bleach can be used if rinsed thoroughly. It warns against phenolic disinfectants, which are toxic. The CDC advises cleaning reptile equipment outside the kitchen, such as in a laundry sink or bathtub.