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Leopard gecko

20 gallon long vs 36 x 18 x 18 for a leopard gecko

The verdict is not close. One is 2.5 square feet and the other is 4.5, and the published minimum is 4.5.

By Brijon M.Last updated

The 36 x 18 x 18 in. A 20-gallon long is about 2.5 sq ft of floor against a published adult minimum of 4.5 sq ft, and it cannot hold three hides along a working thermal gradient. A 20-gallon long is a grow-out.

A leopard gecko walking across a surface

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The comparison

20-gallon long versus a 36 x 18 x 18 in enclosure
20-gallon long36 x 18 x 18 in
Typical footprint30 x 12 in36 x 18 in
Floor areaAbout 2.5 sq ft4.5 sq ft
Against the published minimumBelowMeets
Three hides along a gradientThey fill the floorFits comfortably
Thermal gradient over the lengthMarginal at 30 inWorkable at 36 in
Still sold as an adult setupYes, widelyYes
VerdictGrow-out onlyBuy this

Why 6 inches of width changes the answer

The gap looks small expressed as dimensions and is large expressed as area: 30 x 12 inches is 360 square inches, and 36 x 18 inches is 648. That is an 80% increase, and the published minimum of 4.5 sq ft is 648 square inches exactly.

The practical consequence is about hides. A leopard gecko setup needs three - warm, cool and humid - placed along the thermal gradient. In 360 square inches, three hides occupy most of the available floor, so the gecko is either inside a hide or standing on top of one. In 648 there is usable open floor between them, which is where the animal actually moves.

The gradient argument

A basking surface at 94-97 F (34-36 C) surface; warm hide 90-92 F (32-33 C) at one end and 70-77 F (21-25 C) at the other needs horizontal distance to develop. Thirty inches is short for that, and the result is a warm enclosure rather than a gradient the gecko can choose along.

Pick the 20-gallon if, pick the 36 inch if

  • Pick the 20-gallon long if you are growing out a hatchling and monitoring feeding closely, or quarantining a new animal - both temporary uses with an end date.
  • Pick the 36 x 18 x 18 in if the gecko is a juvenile or adult, or if you are buying once. There is no reason to buy the grow-out first if you already have a juvenile.
  • Pick larger still if you have the space. Floor area is the dimension this species benefits from, and 8 sq ft is genuinely used.

The 36 x 18 x 18 in

REPTI ZOO Front-Opening Glass Terrarium

4.5 sq ft of floor exactly, front-opening, glass. The published minimum with nothing to convert.

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For the humid hide the extra floor makes room for

Sphagnum Moss

Lines the hide at 70-80% inside an enclosure held at 30-40% - the correct answer to shedding problems.

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Frequently asked questions

Is a 20 gallon long enough for a leopard gecko?

Not for an adult. It is about 2.5 sq ft against a published 4.5 sq ft minimum, and three hides along a gradient do not fit. It is a reasonable grow-out.

What is the best leopard gecko enclosure size?

36 x 18 x 18 in as the published minimum, with 4.5 sq ft of floor. Larger floor area is genuinely used; extra height is not.

How many hides does a leopard gecko need?

Three: a warm hide at 90-92 F, a cool hide at the far end, and a humid hide at 70-80% placed at the middle to cool end.

Sources

  1. Leopard Gecko Terrarium Size & Lighting Requirements — ReptiFiles
  2. Leopard Gecko Temperatures & Humidity — ReptiFiles

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