Quick Size Chart
The cheat sheet behind the calculator — floor dimensions, not gallons, are what your gecko actually feels:
| Age Group | Geckos | Minimum Footprint | Common Equivalent |
|---|---|---|---|
| Hatchling (<3 mo) | 1 | 20″ × 10″ | 10-gallon |
| Juvenile (3–10 mo) | 1 | 30″ × 12″ | 20-gallon long |
| Adult (10 mo+) | 1 | 36″ × 18″ | 40-gallon breeder |
| Adult (10 mo+) | 2 | 60″ × 24″ | ~150-gallon class |
Why Size Changes With Age
A hatchling dropped into a 4-foot tank struggles to find food and feels exposed — stress suppresses appetite and growth. An adult in the same tank finally has room for a real thermal gradient, multiple hides, and exercise. Match the enclosure to the life stage, then upgrade as your gecko grows.
Cohabitation Rules
Leopard geckos are solitary by nature. If you still choose to cohabit, the non-negotiables: females only, one quarantine period of 30–60 days per newcomer, extra hides on both ends, separate feeding, and a backup enclosure ready the moment anyone loses tail weight.
Frequently Asked Questions
How big should a tank be for one adult leopard gecko?
Plan for at least 36″ × 18″ of floor space — the footprint of a 40-gallon breeder. A 20-gallon long (30″ × 12″) is often cited as the absolute floor, but modern husbandry standards favor 36″ × 18″ or larger.
Can two leopard geckos live together?
Sometimes — two females can cohabitate in a large enclosure with multiple hides, but results vary and bullying is common. Two males must never be housed together; they fight and seriously injure each other.
Is a 20-gallon long tank okay for an adult?
It is survivable but tight. A 20-gallon long (30″ × 12″) makes a proper warm-to-cool gradient harder to build. If you are buying new, go straight to a 36″ × 18″ enclosure.
How many leopard geckos fit in a 40-gallon breeder?
One adult lives comfortably. For two adults, plan at least 60″ × 24″ so each gecko still gets a full 648 in² of floor space, plus separate hides on both the warm and cool ends.
Do hatchlings need a smaller tank?
Yes — start hatchlings in a 10–20 gallon style enclosure. In a huge tank, prey is hard to hunt and stress rises. Upgrade as they grow: juvenile around 3 months, adult sizing by 10–12 months.