Note: Pet Educate is reader supported. If you make a purchase through a link on our site, we may earn an affiliate commission - at no extra cost to you. This includes links to Amazon.

How Big Do Iguanas Get? [Growth Rate & Growth Chart Per Age]

If you are considering an exotic pet like an Iguana, then naturally you are going to have some questions. Some of which will be about their size. How big does an Iguana get, what is their growth rate like and what are some considerations that you need to take into account? Here is all you are going to want to know

So, how big do Iguana get? The average iguana will range between 5 inches to 7 feet in length when fully grown. This wide variance depends on the species, with each ranging in color, shape, and size. Iguanas will typically reach their full adult size at three years old.

Iguana Size

There are currently 35 existing species with many available to keep as pets, so it is important to be aware of the species you have or plan to adopt.

If you’re looking at iguanas, first and foremost you need to consider the amount of space that you have available, and what you will provide for them.

Many owners like to keep their iguana in a 55 to 70-gallon tank for the first couple of years. They then go on to build a custom cage as their lizard increases in size.

If you have space in your home, you can prepare a room, where they are able to freely roam.

Of course, you will need to ensure that this is a safe environment, with no potential risks and opportunities for escape.

Let us now explore the topic further so that you can get a better understanding of iguanas, their growth, and their potential size.

Iguana Growth Rate

Iguanas grow at an incredibly fast rate; where much of their growth happens in the early years of their lives.

They are sexually dimorphic – which means that male iguanas are considerably larger than their female counterparts by the time they reach adulthood.

When speaking about the size of these creatures, we must be aware of the following terms:

  • SVL – snout to vent length
  • STL – snout to tail length (this includes the vent).

These are the two standard measurements used when understanding and interpreting the size of any reptile; including iguanas.

You will notice how quickly they grow from the time they hatch to just a couple of years old.

Green iguanas can grow up to 2 meters in total and are considered one of the largest species of iguanas.

The following table you help you to understand the type and size of enclosure that will accommodate your growing iguana throughout the various stages of their lives:

Iguana Growth Chart

Age SVL Body Length (Inches)  STL Body Length (Inches) Weight (Pounds)
When Hatching 2.5-3.5″ 6-9″0.2 lbs
Year 18-9″20-27″1-1.5 lbs
Year 2 11-12″28-36″2-4 lbs
Year 3 12-14″30-42″4-6 lbs
Year 4 24-16″35-48″5-8 lbs
Year 5 18-20″45-60″10-15 lbs
Year 6 20-22″50-66″14-18 lbs
Year 7+ 20-24″50-72″15-20 lbs

How Big Is A Full Grown Iguana?

The average large adult iguana (over the age of five) will reach a length of 5-7 feet and weigh about 6-8 kg.

Many people prefer their reptiles to be larger, as this indicates that they are healthy and will be able to handle more petting than a smaller-sized lizard.

Iguanas have muscular bodies, incredible-looking spiking beautiful long tails, and jowls.

Green iguanas are very interesting and can morph into a variety of colors, including red, blue, albino, and blizzard.

Smaller iguana species can also make ideal pets and are far easier to keep in captivity, let’s look at a selection of them:

  • The spiny-tailed iguana – this species comes from Mexico or Central America, it ranges in length from 4.9 to 40 inches.
  • The desert iguana – this species comes from arid regions of America. It can grow to 16 inches in length, but the tail accounts for most of its length.
  • The Fiji crested iguana – sadly, this species is endangered, its numbers are rapidly reducing. They come from dry forested areas in northwestern Fiji. It grows to 30 inches in length and weighs around 300 grams.

When Do Iguanas Stop Growing?

Iguanas typically stop growing around four years of age. That being said, it has been known for iguanas to continue growing for up to eight years old.

Factors That Influence Iguana Size


Iguanas are primarily herbivores, consuming a variety of fruits, vegetables, and leafy greens.

The right balance of nutrients is critical for proper growth.

A diet that is low in proteins and high in calcium, fiber, and vitamins is most beneficial for an iguana’s development.

An iguana’s diet should include a variety of greens such as collard, mustard, and dandelion.

Fruits should be given in moderation as they are high in sugar.

Foods rich in oxalates like spinach, beet greens, and certain types of lettuce should be avoided as they can interfere with calcium absorption.

Feeding your iguana an improper diet or one lacking in variety can stunt its growth and lead to health issues like metabolic bone disease, a common ailment in captive iguanas.

Terrarium Size

Iguanas are large reptiles that require a significant amount of space to move around freely.

A cramped environment can hinder an iguana’s physical development and cause stress, which can subsequently impact its health and growth.

Lighting/Vitamin D Intake

Like most reptiles, iguanas require exposure to UVB light to synthesize vitamin D3, which is crucial for calcium metabolism and healthy bone growth.

Without access to UVB light, iguanas can develop metabolic bone disease, leading to stunted growth, deformities, and other health issues.

The UVB light source should be available for approximately 10 to 12 hours a day to mimic natural sunlight.

It is important to note that UVB light cannot penetrate glass or plastic, so lights must be placed within the enclosure itself, and not on top of a glass or plastic lid.

In addition to providing UVB lighting, dietary supplementation with vitamin D3 can help ensure iguanas get enough of this essential vitamin.

However, supplementation should be used in conjunction with, and not as a replacement for, UVB lighting.

Regular exposure to natural sunlight is also beneficial, provided the temperature and conditions are suitable and the iguana is monitored to prevent escape or predation.


As you can see, Iguanas are not the easiest pet to care for.

They have numerous heating, humidity, misting, and lighting requirements, and they grow quickly in size making it difficult to accommodate them at short notice.

You need to plan and prepare in advance.

The green iguana is an example of a species that lives very well in the wild, but, doesn’t generally do as well in captivity.

It isn’t easy trying to replicate their natural environment. But that does not mean it cannot, nor should not be done.

These should not be reasons to prevent you from getting an iguana but be considered to ensure you know what you are letting yourself in for and know how to take care of them.

You must know what you are doing concerning their care and be willing to invest in their habitat.

These reptiles are amazing to look at, and many people want to be seen with one, but you don’t want to hinder this incredible reptile in any way.

As you can see, iguanas are considered to be large reptiles and can even grow as long as 7 feet in some cases!

But this is not always the case; it depends on the species.

There are smaller-sized iguanas available too, and they are just as beautiful as their bigger counterparts.

So ahead of any adoption, be sure to identify and research the species ahead of time.

Ultimately, iguanas have many excellent traits.

They are very intelligent and take to potty training very quickly. Unlike many reptiles, iguanas recognize their owners which can help you form a bond with them.

If you want a pet that isn’t too clingy and demanding, then an iguana is the pet for you.