How to Tell a Turtles Age (7 Methods)

How to Tell a Turtles Age

How do you know how old is a turtle? Well, the easiest way to find the real age of a turtle is by finding out its date of birth.

Turtles are fascinating creatures, especially when it comes to their longevity and aging process.

Turtles are known for their impressive lifespans. Many species can live for several decades, and some can even surpass a century in age. 

For example the Aldabra giant tortoise can live for more than 150 years.

Turtles age very slowly compared to many other animals. This slow aging is attributed to a slower metabolism and a lifestyle that generally involves less stress and physical damage.

Turtles can take several years to reach sexual maturity. Some species may not be able to reproduce until they are over a decade old. Interestingly, older turtles can continue to reproduce effectively, often without a decrease in fertility.

These are some of the most popular turtle breads

  • Red-Eared Slider
  • Painted Turtle
  • Box Turtle
  • Snapping Turtle
  • Musk Turtles

We’re sharing 7 different ways to determine the age of your turtle.

So, Let’s find out.

How To Tell a Turtles Age

tell a turtles age by its shell
tell a turtles age by its shell

To tell a turtles age by its shell, count the number of rings on a scute. This number can give you an estimate of the turtle’s age. It’s often easier to count the rings on the larger, central scutes.

In some cases, more than one ring can form in a year, or a ring may not form during a particularly stressful or unproductive growth period.

In younger turtles the rings are usually clearer and easier to count. As turtles age, the rings can become less distinct due to wear and environmental factors.

It’s important to handle turtles gently and minimally. Excessive handling can stress the turtle. If you’re examining a wild turtle, it’s best to observe without touching, as interference can disturb their natural behavior and habitat.

Find Turtle Age By Its Size

Use a measuring tape or ruler to measure the straight-line length of the turtle’s carapace (the top part of the shell). This is known as the Straight Carapace Length (SCL). Measure from the front edge of the carapace (just above the head) to the back edge (above the tail).

Carefully measure the belly shell (plastron) at its longest length down the middle. Coupled with top shell length, ratio changes signal age differences.

Document the measuring process with dated notes on distinctive shell markings/anomalies and several top/side photographs including detailed plastron shots to enable long term change analysis.

Regular weight and size recording combined with photographic evidence and shell/plastron condition tracking enables the most accurate age approximations based on physical turtle measurements over long periods of ownership.


Some turtle species have growth charts available, which can provide an estimate of age based on shell length. These charts are often used by herpetologists and turtle breeders.

Use sexual maturity to find turtle age

You can also use sexual maturity to find the estimated turtle’s age.

Using sexual maturity to estimate a turtle’s age is a method that relies on recognizing when a turtle reaches reproductive capability. 

Many turtle species reach reproductive maturity only after reaching a certain minimum size and physiological development, which requires attaining a certain minimum age. This varies greatly by species and gender though.

For example, female snapping turtles may hit maturity between 11-16 years old on average, allowing estimation of a minimum age range. Male snapping turtles mature earlier from 5-7 years.

In sea turtles, variation is high but general averages for maturity are ~25 years in Kemp Ridleys, 30-35 years in loggerheads, 35-40 years in greens, and 45-50 years in leatherbacks.

You can have sexually mature yet still not fully-grown members of a species though, so estimates may be lower than actual age in some cases if based on maturity alone.

Determining sexual maturity itself has challenges too. Blood hormone testing, size & shape changes, nesting behaviors in females, development of secondary sexual characteristics in males can indicate readiness to mate. However these signals are not always distinct.


Skeletochronology is a scientific method used to estimate the age of turtles by examining their bone structure. 

This lab technique examines cross-sections of bones under a microscope. The rings of bone growth can reveal the turtle’s age in years, similar to counting tree rings. But a sample of bone has to be taken and prepared, so it’s more complex.

Skeletochronology requires a bone sample, usually obtained from a living turtle through a minor surgical procedure or from deceased specimens. In turtles, the long bones (like the femur) or parts of the shell are commonly used.

Under a microscope, the bone sections reveal concentric growth rings, similar to the rings seen in tree trunks. These rings, known as Lines of Arrested Growth (LAGs), are formed annually in many species. Each ring typically represents a year of growth, which slows or stops during colder or less favorable seasons.

By counting these growth rings researchers can estimate the age of the turtle. The accuracy of this method depends on the species and the environmental conditions the turtle has experienced.

Skeletochronology is often used in conservation biology to study wild turtle populations, as it provides valuable data on age distribution, growth rates, and longevity, which are crucial for effective conservation strategies.

This method is invasive and in the case of living turtles, should only be conducted by qualified professionals under ethical guidelines. It’s not a method that can or should be used by turtle owners or hobbyists.

Physical inspection

In some cases you can use visual or physical inspection to find turtle’s actual age.

Younger turtles generally have smoother, cleaner shells. As turtles age, their shells may show signs of wear, such as scratches, scuffs, or fading color. However, shell condition can also be influenced by the turtle’s living environment.

The shell often shows characteristic wear, smoothing, chips/cracks, scarring, or anomalies after many years of life. But shell condition can degrade faster in some environments or injuries can accumulate at early ages.

Over decades of life the plastral (belly shell) bone may change proportions in relation to the overall shell size and shape. These subtle changes require an expert eye though.

Each visible concentric ring around the scutes potentially represents a slowed growth period. Attempting counts provides only a minimum estimate. Rings often erode over time.

Signs of advanced aging may appear on the turtle’s skin, eyes (cataracts), and jaw/neck elasticity after many decades. Useful mainly for very mature animals.

CT Scans and Radiography

Radiography and CT scans are advanced imaging techniques that can be used to help estimate the age of turtles. 

Both X-rays and CT scans can reveal the density and structure of a turtle’s bones. As turtles age, changes in bone density and structure occur, which can be indicative of their age.

Similar to the principle of skeletochronology, these imaging techniques can sometimes show growth rings in the bones. These rings, known as Lines of Arrested Growth (LAGs), can be counted to estimate the age, particularly in species where these lines are well-defined.

The scans can provide detailed images of the shell. In some cases, growth rings on the shell might be more clearly visible in a scan than through visual inspection, especially if the shell is worn or damaged.

The overall size and development of the turtle can be assessed through these scans. In conjunction with known growth rates for the species, this information can help estimate age.

While informative, radiography and CT scans still have limitations in precisely determining age. The clarity of growth rings can vary among individuals and species. Environmental and health factors can also influence growth rates, affecting the accuracy of age estimation.

Hatch Date To Tell the age of Turtle

Knowing a turtle’s hatch date or hatch year provides the most straightforward way to determine its age over time.

This method is straightforward if you have a pet turtle that was bred in captivity. 

For pet store bought turtles, purchase receipts may list hatch years that can be used. Or store personnel recall details on clutch hatchings.

Breeders often keep detailed records on when different turtle clutches hatch and individual hatchling sales. Ask to see their documentation.

Date and annual growth marks etched into the turtle’s shells as annuli. Try to locate the first small central mark that likely indicates when hatched. Count outward.

If no hatch record exists for a young turtle, estimate age based on size/species growth rates. Then establish a hatch date for future reference.

For wild caught older turtles of unknown history, work backwards from capture date using general species longevity data to deductively estimate hatch year within a reasonable window.

How To Tell Turtles Gender (Male or Female)

To find out your turtle’s gender look at the tail. Male turtles often have thicker, longer tails to house the penis. The anus will be beyond the rim of the shell in males and on the tail underside. Females have smaller, shorter tails with the anus at the tail rim.

Female turtle’s plastrons (belly shells) are flat for egg laying. Males often have a concave curved plastron to aid mounting during breeding. Very convex female and concave male plastrons help indicate gender.

In many turtle species mature females are considerably larger on average than mature males as an evolutionary advantage for eggs and reproduction. Larger size may indicate female once adulthood nears.

Mature male turtles frequently have exceptionally long, thick nails on their front feet to allow grasping onto females tightly during mating. Less exaggerated on females.

Gently press at the cloacal (vent) opening at the tail to evert a penis if male. This should only be attempted by experts to limit chances of causing internal injury though.

Veterinarians can surgically sex turtles via laparoscopic gonad examination relatively non-invasively if gender remains uncertain by other observable approaches during exams.

Final Words

accurately determining a turtle’s age requires synthesizing multiple data points and techniques. While there is no one foolproof method, some general guidelines and approaches can provide reasonable age estimates.

Key factors to consider are the species and its known longevity, the turtle’s size and weight growth curve, visible shell rings called annuli which may indicate years, reproductive maturity status, and any available records of hatch dates or ownership to indicate a baseline age. 

Visible signs of aging like shell wear, eye/neck conditions, and bone changes seen on x-rays can supplement these core aging criteria.

About Dean Eby

An avid outdoorsman, Dean spends much of his time adventuring through the diverse terrain of the southwest United States with his closest companion, his dog, Gohan. He gains experience on a full-time journey of exploration. For Dean, few passions lie closer to his heart than learning. An apt researcher and reader, he loves to investigate interesting topics such as history, economics, relationships, pets, politics, and more.

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