Male vs Female Leopard Gecko: How to Tell
| Most reliable marker | Hemipenal bulges (males only) |
| Earliest reliable age | ~5–6 months |
| Sex determined by | Incubation temperature, not chromosomes |
The two reliable markers
Pre-anal pores form a V-shaped row directly in front of the vent, between the hind legs — large, dark, and distinct in males, faint or absent in females. Hemipenal bulges are two rounded bumps directly behind the vent at the base of the tail, present in males only; females have a smooth, flat profile there.
How to check safely
Support the gecko gently over a clear container or hold it lightly upside down to view the underside. Never squeeze or press the vent area to force the hemipenes to protrude — this isn't necessary and can stress or injure the gecko.
Timing matters
These features are underdeveloped in hatchlings and young juveniles, so attempts to sex a gecko under about four months are mostly guesswork. Most keepers wait until 5–6 months for a confident read; some males don't show clearly until closer to a year.
Sex is already fixed — appearance just catches up
Leopard geckos have temperature-dependent sex determination: incubation temperature decided the gecko's sex before it ever hatched. Waiting for physical markers doesn't change the outcome, it just reveals it.
Less reliable clues
Adult males tend to run larger, heavier, and more broad-headed than females, and can be more territorial. Size alone overlaps too much between individuals to use as a primary method, but it's a useful supporting clue when comparing geckos side by side.
See the full care guides guide, or browse all 593 info pages.
A single adult leopard gecko needs a 20-gallon long tank as an absolute minimum, with a 36x18 in (40-gallon breeder) footprint now considered the recommended standard — plus a secure lid, an under-tank heater on a thermostat, a thermal gradient, at least three hides, and a shallow water dish.
Set up in this order: substrate, then heat source wired through a thermostat, then hides and water dish, then decor — and run the whole enclosure for at least 24–48 hours to confirm stable temperatures before your gecko moves in.
Hatchlings can start in a 10-gallon tank or tub, juveniles do well in 20 gallons, and adults need a 20-gallon long as an absolute minimum — with 36x18 in (40-gallon breeder) now the widely recommended standard, not just an upgrade.
Heat a leopard gecko enclosure with an under-tank heater and/or overhead heat source (halogen or deep heat projector) wired through a thermostat — a thermostat is mandatory, not optional, and heat rocks should never be used.
Leopard geckos can survive without UVB using dietary D3 supplementation, but current husbandry guidance now recommends low-level UVB (roughly 2–6% T5) as best practice — it improves D3 synthesis, bone density, and natural behavior, and views on it have shifted significantly from older nocturnal-species advice.
Keep ambient humidity around 30–40% across most of the enclosure, with a dedicated humid hide raised to roughly 70–80% to support smooth, complete sheds.