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How To Tell The Age Of A Tortoise [What Can You Do?]

Some tortoise species can live for more than 100 years, so you are going to want to know where you are in their current lifecycle. If you are hoping that your tortoise will tell you or demonstrate in some way their age, you are going to be very disappointed! So what can you actually do to work it out? This is what you need to know.

So, how do you tell the age of a tortoise? The only real way to tell the age of a tortoise is to find out the date it was born. So, unless you know this already, contacting the breeder is going to be your best bet. Failing that, you can only make an educated guess by looking at your tortoise’s shell markings, diet, anticipated growth size, and sexual maturity.

Unless you have that exact date of birth to hand, it’s only ever going to be an estimate.

And that approximation will likely be within 10, 20, or even 30 years of the truth!

Not ideal. Not ideal at all.

So, first and foremost, you should always try and contact the breeder – at least where you got your tortoise from.

Even if it was many years ago. They should keep a record.

Or failing that, you may have a receipt lying around somewhere.

So dig deep.

Other than that, there are other techniques to give you an estimation.

But one thing is for sure; you cannot do this on growth alone.

The growth of your tortoise isn’t connected to its age.

They grow to their full size, and then they stop growing.

So size is not going to be a gauge that you can effectively use.

Instead, you do have options that we will now look at in greater detail.

So keep reading!

How To Work Out A Tortoises Age

You can try to work out the approximate age of your tortoise by comparing its full-grown size to its current size.

Check Your Tortoise’s Anticipated Size When Fully Grown

Look at how big your tortoise is expected to be once your friend reaches maturity.

Most tortoises will reach their maximum size when they are around 15 to 20 years old, although some sub-species mature at 5 to 8 years old.

You can check online for the average male or female length for your subspecies of tortoise, and then measure your friend and compare sizes.

I’ve actually got a few guides here, for reference:

Be sure to compare a female tortoise with another full-grown female of the same sub-species.

For some tortoise species, the female will be larger than the male.

Females also tend to have more rounded shapes with less concave bellies (for storing eggs).

Other species reach the same sizes, regardless of whether the tortoise is male or female.

How To Measure Your Tortoise

Take a tape measure and measure the level above the shell of your pet to check the length.

Hold the tape measure in a straight line without following the curve of the shell.

You’ll have to guess a bit, but the length will give you a good idea of whether your tortoise has reached maturity or not.

As an example, female desert tortoises grow to an average length of 7 to 8 inches (18 to 20 cm).

Adult Sulcata tortoises (the third-largest globally) can grow to 25 to 30 inches long.

So, check the standard adult measurements of your species first.

Here’s another way to measure your tortoise:

  • Put down a sheet of paper on the floor, touching the wall.
  • Put your tortoise on the paper with the shell touching the wall (do this when your friend’s head is tucked inside the shell).
  • Mark the paper where the back part of your pet’s shell ends.
  • Now measure the distance between the mark on the paper to the wall – that’s the length of your pet’s shell.

If Your Tortoise Has Died

One of the most highly reliable methods to determine the age of a tortoise uses skeletochronology testing (counting and measuring growth layers on the tortoise’s bones).

This can only be done on animals who have died.

You can, however, use this method if your friend has passed away and you want to know how old they were.

Experts will cut out cross-sections of the ilium, femur, humerus, and scapula.

Estimating The Age Of A Wild Tortoise

There are actually a couple of different approaches that are used with working out the ages of wild tortoises. Here they are, just for reference.


If you find yourself wanting to estimate the age of a wild tortoise, the best practice is a ‘mark and recapture’ method.

Experts will identify and tag young tortoises – usually no older than 2 years old – and then retag them at regular intervals, which will enable them to keep track of their age and health.

Some tortoises are tagged electronically. Either way, tortoises mature slowly, so both methods require a long-term commitment!

Looking At Fungal Growth

Another factor you can look at to guess an approximate age for a wild tortoise is to look at the amount of fungal growth on their shell.

Simply put, the more fungus on the shell, the older the wild tortoise.

Scientists usually take samples from the shell and then test them to come up with a general estimate of the tortoise’s age.

Can You Tell A Tortoise’s Age By Its Shell?

You can’t tell a tortoise’s exact age just by looking at its shell.

There is an old wives’ tale circulating the internet that says you can tell the age of your tortoise by counting the rings on its shell, but this is no more than a popular myth (see below).

Counting Rings On The Shell

While counting rings won’t give you an exact age for your pet, you can use this method to arrive at a very rough approximation.

You will see that there are many oblong patches on the top of the shell of your friend, called scutes. These patches grow in size as your tortoise matures.

Scutes are similar to fingernails – they’re made of keratin, with the outer layer of scutes being the oldest. Land tortoises won’t shed their scutes, but if they dig burrows, the scutes can wear down over time.

Your tortoise’s ribs and spine are attached to the bones of their shell (carapace).

As your tortoise grows, the scutes expand, creating visible growth rings.

However, growth rings don’t happen at a steady rate of one per year.

Rings actually occur during growth spurts, which can happen at any time and are dependent on various other factors such as food availability and other environmental conditions.

If your tortoise has a diet with the right amounts of calcium and protein, these nutrients can trigger growth spurts that will then leave a wider space between scute rings than a tortoise who hasn’t had such a varied diet.

You will notice that the scute rings grow in pairs: a thicker ring develops over the course of a year, with a thinner ring next to it.

If you were to count 20 pairs of rings, you could assume that your tortoise is 20 years old.

However, because rings grow due to…, any age that is determined in this way is only a rough estimate. A tortoise with 30 pairs of rings could be anywhere from 10 to 50 years old!

Life Stages Of A Tortoise

You can look at the various life stages of your tortoise to help you estimate their age.


Usually, a baby tortoise will have a soft shell until about 6 to 8 months of age. The softer the shell, the younger your friend is likely to be.

However, to check the softness of your pet’s shell, be gentle! Don’t press hard on the shell, or your friend may get hurt.

Not everyone knows that your tortoise’s shell (or carapace) is part of their bone structure. This means that if their shell is damaged, they do experience pain.

Sexual Maturity

Both female and male tortoises tend to reach sexual maturity anywhere from 4 years to 15 years old, depending on the species.

Check at what age your tortoise’s breed will come into sexual maturity first.

If your female tortoise is laying eggs, or if your male is mounting females, at least you can be sure of your friend’s minimum age.

Old Age

Very old tortoises – those who are reaching 100 years old – often have smoother shells.

If a tortoise has been alive for a very long time, its shell can become slightly eroded from rain and sand (so this applies to tortoises who live most of their lives outdoors).

Ridges, bumps, and rings can become smooth over years and years.

Once again, a smooth shell only indicates that the tortoise is fairly old.

The amount of erosion on the shell of a tortoise is directly influenced by the environmental conditions in which it spends most of its time.

Other Ways To Get Help Estimating The Age of Your Tortoise

Of course, you can always take your tortoise to your vet, who might take a blood sample and send it to a lab for testing.

Laboratory blood tests can look for age markers using your tortoise’s metabolic profile.

While this method is only good for insights rather than specific age, it can still give you a rough estimate of the age of your tortoise.

Usually, though, vets will use the same observational techniques as we have described here.

You can, however, benefit from their experience, particularly if they have a lot of knowledge about tortoises and other reptiles.

The advantage of having a blood test done is that these tests can be helpful to detect illnesses or other health problems.

Your vet may also look at how your tortoise behaves.

If your tortoise eats less, moves more slowly, and shows signs of wear and tear on its body, those are all typical signs of older tortoises.

Some experts can use these visual clues to make an educated guess as to the age of your friend.

The accuracy of these guesses is, at best, perhaps within 3 to 5 years for a young tortoise and maybe as much as 10 years or more for an older animal.

The older the animal, the less accurate the estimation is likely to be, as it is next to impossible to know if a tortoise is 30, 40, 50, or 60!


In all honesty, there are not really many, if any ways to know for sure the age of your tortoise outside of referencing their birth date.

And that can be tricky due to the fact they live so long.

That being said, you should be able to get a rough idea. And if you can’t a vet or reptile expert should be able to get a little closer!

And perhaps start record keeping from here on in!