How to Sex a Crested Gecko? (4 Proven Methods)

Determining the sex of pets like dogs or cats might be straightforward, but when it comes to reptiles like the crested gecko, the process becomes considerably more nuanced. You’re not alone if you’re scratching your head trying to figure out if your adorable gecko is a male or a female.

With unique physical characteristics and behavior patterns, sexing a crested gecko is possible but it requires a keen eye and the right expertise.

In this comprehensive guide, I’ll walk you through the exact indicators to look for when your crested gecko reaches sexual maturity. I’ll provide actionable steps to safely and accurately determine their sex, ensuring you handle your pet with the care they deserve—no spooking or injuries allowed.

When Can You Sex a Crested Gecko?

The best time to identify the sex of your crested gecko depends largely on its age and size. With authoritative advice from veterinarians and reptile care experts, this section aims to provide a clear, fact-based guide to answer all your pressing questions.

When Do Crested Geckos Reach Sexual Maturity?

Crested geckos reach sexual maturity between 15 to 18 months of age. According to Dr. Susan Horton, a veterinarian with expertise in exotic animals, this is the period when their reproductive organs are fully developed, making it easier to identify their sex.

What Age Can a Crested Gecko be Sexed?

It’s generally possible to make an initial determination of a crested gecko’s sex when they’re around 6 to 7 months old. However, for more accurate results, it’s recommended to wait until they reach sexual maturity.

How Big Do Crested Geckos Need to Be to Sex?

The size of the gecko plays an essential role in sexing them accurately. Typically, a crested gecko should weigh around 35-40 grams before you can accurately determine its sex.

Methods for Sexing Crested Geckos

There are 4 different methods you can use to determine the sex of your crested gecko. The most accurate way to sex a crested gecko is through identifying hemipenal bulges and preanal pores.

Method 1: Identify Hemipenal Bulges

While there are several methods to sex crested geckos, identifying hemipenal bulges is one of the most reliable and straightforward techniques.

Why This Method Is Reliable:

  • Hemipenes are exclusive to male crested geckos, making this a definitive gender marker.
  • The physical difference is visible and does not require any invasive procedures.

What Are Hemipenal Bulges?

Hemipenal bulges are basically small, protruding sacks located at the base of a crested gecko’s tail, right above the vent. They are called “hemipenal” because they house the hemipenes, which are the male’s reproductive organs. These bulges are a tell-tale sign that you’re looking at a male crested gecko. In females, this area is usually flat and smooth.

How to Identify Hemipenal Bulges


First off, the gecko should be old enough for this characteristic to be visible; typically, they become noticeable around 5-6 months of age or when the gecko weighs about 12-15 grams.

Once you’re confident your gecko is mature enough, place it in a calm, well-lit setting. Gently lift the tail to expose the area above the vent and look for the protrusions. If you’re still unsure, a magnifying glass can be used for a more detailed examination.

Precautions and Common Mistakes to Avoid

  • Be careful not to grip the tail too tightly; crested geckos can drop their tails as a defense mechanism.
  • Also, ensure your gecko is of an appropriate age and size, as trying to sex a too-young or too-small gecko can be stressful for the animal and might not yield accurate results.

I’ve found that back-lighting the area with a flashlight can sometimes make the hemipenal bulges easier to see. And if you’re still uncertain after your inspection, consult a vet experienced with reptiles for a second opinion.

Method 2: Identify Pre-Anal Pores

This method is a bit more nuanced than simply looking for hemipenal bulges, but it’s equally effective to sex a crested gecko. In fact, distinguishing pre-anal pores is a surefire way to sex your crested gecko accurately.

Why Pre-Anal Pores Matter

Pre-anal pores are tiny dots located just above the vent area in male crested geckos. They are usually absent or less evident in females. Here’s why they’re crucial for determining your pet’s gender:

  1. Explicit Indication of Sex: The presence or absence of pre-anal pores is a direct indicator of the gecko’s sex.
  2. Ease of Identification: Once you know what you’re looking for, spotting these pores is fairly straightforward.

Steps to Identify Pre-Anal Pores

To identify these defining features, follow this step-by-step guide:

  1. Prepare Your Gecko: Gently hold your crested gecko, ensuring it’s comfortable and not stressed. Stress can make this process more difficult for both you and your pet.
  2. Ideal Lighting Conditions: Make sure you have adequate lighting. A flashlight can be particularly helpful.
  3. Positioning: Turn your gecko so its ventral side is facing you. It’s easier to do this with a helping hand, but it’s manageable alone.
  4. Locate the Vent: The vent is the opening located at the base of the tail. The pre-anal pores, if present, will be just above this area.
  5. Examine the Area: Carefully look for tiny, uniform dots arranged in a V-shape above the vent. These are the pre-anal pores.
  6. Photograph for Records: It’s advisable to take a clear picture for future reference, especially if you plan to breed your crested geckos.

Precautions and Tips

  • Crested geckos are delicate creatures. Handle with care to avoid causing stress or harm.
  • If you’re uncertain, it’s always a good idea to double-check after a few days.
  • If you’re having difficulty, don’t hesitate to consult with a herpetologist or an experienced reptile keeper.

Method 3: Physical Differences

Physical features can also help in identifying the sex of a crested gecko. The three main physical features to look for include; the size of the body and head, the size of the cloacal spur, and the size of calcium sacs.

1. Body and Head Size

Male: Generally, males have a more robust build with a broader head and body compared to females.

Female: Females tend to have a more slender build and their heads are generally not as wide as those of males.

Observing these size differences requires ongoing scrutiny; it’s not something you’ll easily spot on day one, especially in younger geckos.

2. Cloacal Spur Size

First, let’s clarify what a cloacal spur is. These are tiny, pointed scales located near the vent, which is the combined urinary and reproductive opening of the gecko. They serve as a key distinguishing factor in sexing crested geckos.


Male: The cloacal spurs in males are generally more prominent. These spurs are larger and more defined, making them easier to spot.

Female: Females have cloacal spurs as well, but they are often smaller and less noticeable.

When inspecting this area, exercise caution. The region is sensitive, and your gecko’s comfort should always be the priority.

Size of Calcium Sacs

Crested geckos and other reptiles, calcium sacs are small, specialized storage organs found in the mouth, usually attached to the roof. These sacs contain calcium, which is an essential mineral for various biological functions including bone health, nerve function, and in the case of female reptiles, egg production.


In crested geckos, these calcium sacs are particularly important for females. The calcium stored in these sacs serves as a reserve that the females can draw from during the physically demanding process of laying eggs. Calcium is a critical component of eggshells, and a deficiency could lead to severe health issues such as metabolic bone disease or complications in egg-laying (also known as “egg binding”).

You can usually spot these calcium sacs during a routine health check. Open the gecko’s mouth gently and look at the roof of the mouth; you should be able to see one or two small, whitish sacs. These are the calcium sacs.

Male: Typically lack calcium sacs.

Female: Have noticeable calcium sacs located in the roof of their mouths.

Method 4: Sexual Behavior

While physical attributes like hemipenal bulges and pre-anal pores are reliable indicators, sexual behavior provides additional cues that can be extremely helpful, especially for beginners.

Specific Sexual Behaviors to Observe

In crested geckos, sexual behavior is often straightforward, making it an ideal method for sex identification. Here’s what to look for:

  • Mating Position: Male crested geckos generally initiate the mating process and will usually be found on top, while the female is underneath. This dominant position by the male is a strong indicator of its sex.
  • Courting Rituals: Males tend to be more active in initiating courtship. They may produce soft chirping sounds and make deliberate movements towards the female.
  • Aggression: Male crested geckos can show signs of aggression or territorial behavior, especially when another male is introduced into their space.

These behaviors usually manifest as the geckos reach sexual maturity, which typically occurs around 15 to 18 months of age. So, if you’re dealing with very young geckos, you might have to wait a bit before these behaviors become apparent.

Variations and Exceptions

Remember, nature is not always black and white. There are exceptions to every rule:

  • Some females may display aggressive behavior, often mistaken for male behavior.
  • Young or less dominant males may not always initiate courtship and could appear submissive, especially if there’s a more dominant male present.

Frequently Asked Questions

Can Crested Geckos Reproduce Asexually?

Contrary to some beliefs, crested geckos cannot reproduce asexually. All geckos have definitive male or female reproductive systems, and it’s essential to identify these for accurate breeding or care.

When Can You Tell the Sex of a Crested Gecko?

By 6 to 7 months, initial determination is often possible, although waiting until sexual maturity at 15 to 18 months is advised for definitive identification.

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