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7 Methods On How To Tell A Turtle’s Age

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There are several ways to determine a turtle’s age, but some are better than others. Turtles are reptiles, which means they belong to the class Reptilia.

Western painted turtle walking on the ground

They are also known as tortoises because their shell resembles a tortoise. Turtles come in various sizes, shapes, and colors. Some species are even endangered due to habitat destruction or overhunting.

There are several ways to determine the age of a turtle. The easiest way is to look at its teeth. If the tooth enamel has worn down, then the turtle is older than it appears.

Another method involves counting the number of growth rings on the shells. Growth rings form every year, and each ring represents approximately one year.

In this article, we will discuss the 7 methods which you can use to determine a turtle’s age.

How Long Can Turtles Live For?

Turtles live for a very long time. The most effective way to know a turtle’s age is by knowing the date at which they hatched.

However, all the methods we are going to be talking about will give you an estimate of a turtle’s age, it can be difficult to know the exact age if you don’t know the hatch date.

Yet, something you may be aware of is that turtles are known for having incredibly long lifespans. Some tortoises can live for around 150 years.

For example, the giant Galápagos tortoise is known for its lifespan of around 177 years. Even sea turtles have a long lifespan and can live for around 80 years.

It is difficult to know the age of a sea turtle due to their habit in the water and in the seas and oceans. Thus, it is more difficult to track. Even tortoises that are in captivity sometimes they can be moved around, and thus it can be difficult to determine their exact age.

1. Rigidity Of The Shell

Yellow bellied slider on white background

As long as your turtle isn’t a soft shell, you can look at the rigidity of your turtle’s shell. This allows you to know if your turtle is either under 6 months or older.

This is because a small turtle that has a soft shell is typically considered to be only around 6 months old or below.

The softer the turtle’s shell is, the younger in age the turtle is. This is due to the turtle’s shell needing time for it to harden. This hardening begins when the turtle is between 6 and 8 months old.

Be careful when touching a turtle’s shell; just gently touch it but don’t press on it, as the shell is part of the turtle’s bone structure. You don’t want to cause harm or damage to the shell or the turtle.

Also, the tutelage houses its internal organs on the inside of the shell. So if you press too hard, you could damage an organ.

Something to be aware of is that a soft shell can be a result of bone disease. Also, some turtles are known as soft shells, but their shell will feel much different from a typical hard-shell turtle.

A soft shell will feel like leather. While a baby turtle, the shell will feel quite spongy.

2. Weighing And Measuring The Length Of The Shell

A turtle will commonly reach their maximum length once they have reached maturity. Sometimes their length can increase, but this process is quite slow.

As long as you know the species, you can then measure in a straight line the shell’s length. This will then let you know whether the turtle is actually sexually mature. This can then help you determine the age of the turtle.

However, maturity can be reached in some species at different ages. A red-eared slider will typically reach maturity at around 5 to 6 years old. Their shell will be 10 to 15 cm in length.

The gender of the turtle will also affect the length as well. Thus, this isn’t always the most accurate method, as some turtles grow quicker than others.

3. Sexual Maturity

As we have already briefly mentioned, particular turtles will reach sexual maturity at certain ages. This isn’t a completely accurate method to determine a turtle’s age, as a lot of breeders like to use size to determine the sexual maturity of a turtle.

It is worth doing some reach to see what ages a turtle will reach sexual maturity.

A sexually mature female is known to lay eggs even if they haven’t mated. In this instance, this female, you can assume, has reached sexual maturity. However, depending on the particular species, you can try to estimate that turtle’s age.

4. Visual Cues

Visually, a turtle can tell you a lot about its age. For example, an older turtle will eat much less and much slower than a younger turtle.

Especially in the wild, an older turtle will also have much more wear and tear on its shell. It can look quite worn out with lots of scratches and even dents.

It is known that a turtle with a smooth shell will generally be over 100 years old. This is because the older a turtle gets, the smoother the shell will become.

This is due to the erosion from rain and sand that the turtle’s shell is exposed to. So, the bumps, rings, and ridges will smooth out over time.

5. Skeletochronology Test

This test is typically done after death to determine the death of wild turtles. Generally, the ilium, scapula, femur, and humerus bones are inspected.

With this test, the counting of the skeletal tissue is done to try to determine the growth rate and age of the turtle. This is normally a very accurate way of estimating age. However, the main downside is that it can only be done once the turtle has died.

Although, it is great for reaching out to turtle lovers who want to study turtles and particularly sea turtles, to understand them more.

6. Counting The Rings

Turtle walking on grass

Measuring the carapace will give you an insight into whether the turtle is mature. However, if you want to understand the turtle’s age more, then you should count the rings on your turtle’s scute.

The scutes are the plates that make up the turtle’s shell. These can give you a rough age, as it shows periods of growth.

A ring will make you aware of a growth spurt the turtle has had. However, how much your turtles grow does depend on how much they have eaten.

Sometimes the rings can differ in size and color. Although for wild turtles, the smaller rings can showcase in winter when there isn’t much for the turtle to eat, so they don’t grow as much. Yet the opposite for summer and the warmer months, thus larger rings.

To try to estimate the age, divide the number of rings on the shell by 2. So if a turtle has 16 rings on the plates of its shell, then you can estimate that the turtle may be around 8 years old.

7. Hatch Date

The best way to estimate a turtle’s age, yet with them, still alive, is by the hatch date. If you know the hatch date of a turtle, then you will be able to calculate their age with accuracy.

Even so, some other ways will also allow you to estimate a turtle’s age. This way, you will be able to determine the actual age.

However, keeping a track of a turtle’s hatch date isn’t that easy, unfortunately. This is because some turtles live for so long and if they are captive they move around as well. So the true age of that turtle can be lost over time as they move around.

However, it is also important to keep track of your turtle’s age in case your vet ever asks for it.

Frequently Asked Questions

What Is the Oldest Known Turtle?

Jonathan is a Seychelles giant tortoise who is still alive today at the grand age of 190 years old! Yet there is a sea turtle in China that is believed to be over 400 years old.

Why Do Turtles Live So Long?

It is believed that turtles have a low metabolic rate, and as it isn’t a very active animal, this is what allows them to live for so long. Also, turtles can live for very long without food, which also allows them to prolong their life span as well.

How Long Do Sea Turtles Live?

Sea turtles can live for a minimum of 50 years or longer. Yet they have a similar lifespan to a human, so they don’t live as long as some other species of turtle.


We have given you 7 ways in which you can try to determine the age of your turtle. Some methods have more success and are easier than others. Hopefully, now you know how to estimate the age of your turtle, so you can get an insight into how old they really are!

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About the author


Kerry White is an avid dog lover and writer, knowing all there is to know about our furry friends. Kerry has been writing for PetDT for three years now, wanting to use her knowledge for good and share everything she can with new dog owners.Kerry has two dogs herself - a German shepherd called Banjo and a chocolate labrador called Buttons. Kerry knows more than anyone how adjusting to new life with a puppy can turn your life upside down, and she wants to ease some of the burdens through her articles.