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How To Tell How Old An Iguana Is (Age By Size Chart)

Have you recently adopted an adult iguana?

Are you curious how old your iguana is?

If you are looking into the age of your iguana, you might wonder:

How can I tell how old an iguana is?

An iguana’s age is usually determined by its length and weight. However, this age will be approximate due to factors affecting an iguana’s growth, such as tank size, diet, genetics, and tail loss. If you purchased your iguana from a breeder, they would give you a more exact age based on its hatched date.

For more information on how to determine the age of an iguana, keep reading this article.

how to tell how old an iguana is

How Can I Tell How Old An Iguana Is?

Determining the age of an iguana isn’t an easy feat.

For one, they can’t tell you when their birthday is, and for another, it isn’t easy to make an exact determination because all iguanas will be different, just like people.

Unless you were given exact information from a breeder on the date of their hatching or you bred the animal yourself, it is likely you won’t know precisely how old your pet is.

There are ways to determine the approximate age of your iguana to give you a general idea.

Understanding the approximate growth rate and size of iguanas can help you determine the age of your pet.

Here we have compiled a chart showing the approximate sizes of iguanas and at what age they should hit these milestones.

The chart features measurements from snout to vent length (SVL) and snout to tail length (STL).

These are two common ways you will often see when measuring iguanas.

We have also included a weight approximation to help you decide the age of your pet.

Age SVL (inches): STL (inches): Wgt/Lbs:
Hatchling 2.5-3.5 6-9  
3 Months 4-5 12-14  
6 Months 6-7 18-20  
1 Year 8-9 20-27 1-1.5
2 Years 11-12 28-36 2-4
3 Years 12-14 30-42 4-6
4 Years 14-16 35-48 5-8
5 Years 18-20 45-60 10-15
6 Years 20-22 50-66 14-18
7 Years 20-24 50-72 15-20

Growth will be much more rapid from the hatchling stage through the first few years and have the largest jumps.

Male iguanas will also be larger than females of the species, with the females only reaching lengths as long as 5′ feet from snout to tail.

Males can reach sizes measuring as long as 6′ or 7′ feet.

iguana length


When you see the measurements of iguanas listed, you will often see both SVL and STL numbers.

Both are common ways to measure the animal, but one is slightly more dependable than the other.

The snout to vent measurement or SVL is more accurate than the length of the full snout to tail tip.

This is because many iguanas will lose their tails, even in captivity, as juveniles, or at another point in their lives.

When an iguana loses their tail, it will regrow it, like many other reptiles, but it will be slightly shorter and darker than the original.

An iguana can detach their tail when they are spooked or feel threatened in captivity.

In the wild, this ability offers them a way to escape from their predators.

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Why Measurements Aren’t An Exact Way To Determine Age

At A Certain Age, Iguanas Stop Growing

Iguanas will reach maturity at around two to three years old but continue to grow steadily until they reach five to seven years old.

Once they stop growing, you will have a more challenging time telling how old they are.

These first five to seven years will offer the best chance for you to determine the age of your iguana.


All iguanas will be slightly different and grow differently.

Think about all the people you know and how they are all different sizes, heights, and weights.

Some people will even mature at different ages, and animals, including the iguana, are no different.

Genetics can play a significant part in how large the animal will get and the rate they get there.

Treatment And Health

How the animal has been treated will factor in its size and its growth rate.

If the iguana has been mistreated or held in too small of a cage, its growth will likely be stunted, and you will not be able to tell the age based on the growth chart accurately.

sick iguana

Iguana’s who have been kept in too small of an enclosure can experience stunted growth and not reach their full potential.

In addition to the size of the enclosure, a lack of proper UV lighting and temperature can impact the health of the iguana and how large and quickly they grow.

They can see the neglect in the amount of food they are given.

On the other hand, if they are fed well, especially at a young age, their growth rate can jump exponentially.

If they are fed every day at a young age, you will see rapid growth in your iguana.

Neglect in any of the ways mentioned can lead to poor health of the animal.

Be sure to research proper care and habitat for an iguana before you bring one into your home.

Like any animal, they will require specific care if you want them to grow and flourish.

When you rescue a previously neglected iguana, you will have to build trust, but once you provide them with good food and a proper habitat, they too will flourish and have a chance at a great life.

These rescues may prove difficult in identifying their age, but given extra care, they will make for a good pet.

To ensure you’re providing the best care, read our article on how to raise an iguana.

Iguana Age Identification Made Simple: Tips and Techniques

While you might not have an exact idea of your iguana’s age, you will get a general idea if you look at the size of your pet.

With this information, we hope you will have a better idea of how to determine the age of your iguana.

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