How To Age A Box Turtle

How do you age a box turtle? 

Unless you raised your turtle from a hatchling or got it from someone who did, you’re probably curious about your turtle’s age. 

After all, a box turtle is a relatively long-term commitment – a healthy box turtle can live well over 25 years as a pet, with some box turtles allegedly reaching over 100 years old in captivity. 

A box turtle will also have different needs throughout its life cycle. 

A juvenile box turtle’s diet will require more animal protein than an adult turtle, and hatchlings need much more frequent feedings. 

Awareness of your box turtle’s age will help you provide the care it deserves and prepare you for a long and happy life with your pet.

how to age a box turtle

How To Age A Box Turtle

Although no method will give you an exact answer, get a good idea about your turtle’s age by counting the growth rings on its shell. Box turtles’ shells are separated into little raised plates over its back, called a scute. Take the number of rings and divide by two to get the turtle’s age in years. 

You’ll notice inside each scute the markings of two kinds of alternating rings. 

Thin rings of another color separate wide rings of one color. 

Both juvenile and adult Eastern box turtles will have these scute rings. 

The rings’ width indicates how well the turtle ate during this period – wide rings indicate a period of plentiful food, and thinner rings develop during hibernation or a season of scarcity. 

So a rough estimate for its age, not exact age, is to count a thin band plus a narrow band on their shells as a year. 

Eastern box turtles also develop these markings on their belly plates, but counting these is not ideal – you will find turtles do not like being turned upside down, and these rings are harder to see.

If your box turtle was caught in the wild or was injured, the rings might not be clear. 

When the turtle reaches 15, it becomes harder to get an exact age because the rings get so close together.

If your turtle is not yet an adult, guess at its age by measuring the length of the body.

Telling a Box Turtle’s Age By Size

Box turtles will reach a length of 4.5 to 6″ inches (15 cm), with captive turtles maxing out at 8″ inches (20 cm). 

Males are typically smaller than females. 

Males and females grow rapidly in the first 4-5 years of their life – expect a box turtle to hit 3-4″ inches (10 cm) by their first year, and growth slowing dramatically after 10 years. 

Many factors contribute to your turtle’s growth, including diet, basking time, genetics, males vs. females, habitat, and the box turtle’s specific species. 

Ask your veterinarian, or consult a size chart for your particular species of turtle for the most accurate estimate of a juvenile turtle’s age. 

The length of the turtle is measured from the head to the tip of the tail. 

Below, see an example size chart for a typical Eastern Box Turtle.

Eastern Box Turtle Size Chart

Keep in mind every turtle will be different, and its ultimate length is determined by many factors. 

AgeLength in Inches (Centimeters)Growth rate per year
Hatchling1” – 1.25” inches (3.2 cm)Up to 4” inches (10 cm)
1-5 years1.25”-4” inches (10 cm)0.4” – 0.5” inches (1.2 cm)
5-10 years4” – 4.8” inches (12 cm)0.3” inches (1 cm)
10+ years4.8”-6” inches (15 cm)0.08” inches (.2 cm)

As you see by the chart, different turtles can reach very different sizes at the same age. 

Once the Eastern box turtle reaches sexual maturity (at around 4-5 years), it becomes much more difficult to gauge your turtle’s age based on size. 

Aging Captive Bred Vs. Wild Caught

Whether your box turtle was bred in captivity or caught in the wild will affect many things about its longevity and your ability to determine its age. 

Can I Keep a Wild Western or Eastern Box Turtle?

The short answer is: Probably not. 

Many humans keep box turtles as pets, and you may find them wandering roads, fields, and backyards across the Central and Eastern United States. 

However, many states have laws against keeping wild turtles as pets. 

Wild turtles will not adjust well to captivity and often die of stress. 

The turtle you see out in a field also has the potential to carry diseases, including salmonella. 

It’s best to find your pet turtles from a reputable breeding expert or rescue.

Wild box turtles will generally grow more slowly. 

Since they don’t grow while hibernating, a wild box turtle will reach full size later than a pet box turtle. 

However, due to the way rings grow (feast vs. famine seasons), it might be easier to count the rings on an Eastern box turtle you come across outside.

Box Turtles As They Age

It’s important to know the age of your pet turtle to ensure an adequate diet and maximum growth potential.

Male and female box turtles are omnivores, meaning they need plants and protein.  

Juvenile box turtles require a higher protein ratio in their diet (more insects) than fruits, vegetables, and other plants. 

In the wild, they can forage for what they need, but as a pet, it’s up to you to find out the proper diet for every stage of your turtles’ lives. 

Juvenile box turtles generally need to be fed once a day, whereas adults may be fed three times a week. 

It’s also recommended you give young turtles daily supplements. 

Always consult your veterinarian to ensure you’re giving your Eastern box turtle the nutrition it needs.

Final Thoughts

Box turtles need adequate room to thrive and grow. 

A hatchling and a fully grown turtle need different sized spaces. 

Know how old your box turtle is and adequately prepare for its habitat when it is fully grown.

It’s both important and interesting to age a common box turtle. 

You should see the rings on both baby and adult and wild and pet box turtles. 

A quick look at its size can give you an idea of whether you’re looking at a juvenile or adult Eastern box turtle. 

Keep an eye on how fast your turtle is growing as an indication of its overall health, and always consult your vet at every stage in your turtle’s average life span. 

With proper diet, habitat, and handling, your turtle should be a great pet for years to come.


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