How Long Does It Take for a Turtle to Grow (To a Full Adult)?

Even though turtles are a fairly common household pet, they are an animal that a lot of people do not actually know much about. This isn’t restricted to people who have very little interest in turtles.

In fact, even new turtle owners might still lack this basic knowledge. One important piece of knowledge being how long it takes for a turtle to grow to adult size.  

Whether you are a new turtle owner, keen to know when your new baby becomes an adult, or someone who is simply interested in finding out something new, you are in the right place.

In this guide, we’ll be giving you absolutely all the information that you need to know about identifying when your turtle has grown to their adult size. So keep on reading to find out. 

How long does it take for a turtle to grow?

With some animals, such as cats and dogs, people generally know how long it is going to take for that animal to reach their adult size. By the age of 1 most dogs and cats will be fully grown, but they have a much shorter life expectancy than tortoises and turtles. So, how long does it take for a turtle to reach their adult size? 

A typical pet turtle will live anywhere between 10 and 80 years, with the majority falling towards the higher end of this scale. This is significantly longer than the life expectancy for other animals, such as dogs and cats, so it makes sense that it takes a lot longer for turtles to grow to their full adult size. 

There is no specific age at which a turtle reaches their adult size. This is because so many factors have an influence on this. From the species of the turtle to their living conditions, there are so many things that will impact this.

But, most turtles will reach their adult size somewhere between the age of 5 and 8 years old. Some turtles will take longer than this, however all turtles will reach their adult size by the age of 10. 

As a turtle owner, there are lots of things that you need to consider which you might not have thought about before. From the size of their tank to the food that you feed them, all of these things will impact the growth of your turtle.

So, let’s take a look at some of the things that can affect the time in which it takes for your turtle to grow.  

Things that Could Affect the Growth of a Turtle 

As we have said, there are lots of different things that can impact how your turtle grows, and the time that it takes for your turtle to reach their full, adult, size. To help you out, let’s take a look at some of these factors in a little more detail. 


Just like with all animals, the diet that you feed your turtle will have a huge impact on their life and health. Turtles live a lifetime that is comparable to the life expectancy of humans, so feeding them unhealthy food can have the same impact on their health as it can on your own. 

You often hear that you should restrict the amount of unhealthy food that you feed children, so bear this in mind when you are feeding your turtle. If you feed your turtle unhealthy food, or insufficient amounts, this will have a direct impact on their growth. So always ensure that you are feeding your turtle a good, healthy diet. 


We mentioned this briefly earlier, but another thing that will greatly impact the rate of growth in your turtle is the habitat that they are living in. By this, we mean the tank that you are keeping them in.

Turtles grow quickly, and a lot of new turtle owners make the mistake of buying a tank that is too small, which can have an effect on the growth of your new pet. 

Additionally, things such as quantity and quality of water, hiding spots, basking spots, and UV visibility will have a huge effect on how quickly your turtle grows to their full size. Habitat plays a massive role in keeping your turtle happy, so always ensure that their tank is perfect. 


Something else that will have a massive effect on how quickly turtles grow is the species that they belong to. Different species will have different rates of development, and you will often find that smaller species of turtle grow significantly quicker than larger species. 

You will also find that other genetic factors, other than species, can affect the rate of growth in turtles. Things such as sex and subspecies can also have a massive influence over this.

This is why you might notice a difference in the rate of growth if you have previously had a female turtle and currently have a male one. Even if they are the same species. 

How to Tell If Your Turtle is Fully Grown

The best way to monitor growth in your young turtle is to regularly measure their shell. By this, we mean the width and length of the shell. Do this regularly throughout their early life, and this will allow you to monitor the rate at which your turtle is growing, and also allow you to keep checking that they are healthy. 

If you begin measuring your turtle’s shell when they are young, you will also be able to tell if they are fully grown using this method.

If you continue to measure your turtle’s shell regularly and then begin to notice that the measurements plateau, this is a good sign that your turtle has reached their full adult size. Cross-check their age with the expected age for adulthood for that species of turtle, and it will allow you to see if your turtle is fully grown. 


In short, most turtles will reach their full adult size by the age of 5 to 8 years. However, things such as species, diet, and habitat will have an effect on this. So, don’t be alarmed if it takes a little longer for your turtle to reach their full adult size.