How Big Do Box Turtles Get?

If you own a box turtle, you might be wondering how big do box turtles get? Box turtles normally grow up to 5 – 7 inches.  

With proper diet, environment, and care, your Box Turtle can live up to around 20 to 25 years.

How big is a fully grown box turtle?

Box Turtles are fascinating creatures that make a terrific choice for a pet. Like many other animals, gender does sometimes impact the overall size and height of a box turtle. The female box turtles are larger than males. Both male and female box turtles grow at a slightly different rate and have slightly different adult sizes.

Let’s have a look at the box turtle’s average size.

• The average size of male box turtle: 5 inches to 6 inches
• The average size of female box turtle: between 6 inches to 7 inches

How long does it take for a box turtle to be fully grown?

Their transformation from baby turtle to adult box turtle is not as dramatic as in many other pets, but they still do grow. Generally, the box turtles can grow up to 4 inches during their first year.

After the first year, the growth rate of box turtles drops. A box turtle grows 0.5 – 1 inches per year after the first year and this continues for several years. Once the turtle reaches its maximum size, the growth ceases or becomes slower. Remember that these are averages and may vary slightly.

As you can see from the chart below, box turtles usually become fully grown between the ages of 4 and 6. However, these are merely averages. Your box turtle might reach its full size a little before or after these ages.

While an indoor enclosure can certainly accommodate an adult box turtle, they usually thrive in outdoor enclosures.

To learn about other species of turtle, check out my article on How big do turtles get?

Factors that affect box turtle’s growth

Here are some factors that affect the growth rate of box turtles:

• Genetics: Just like most other species, your box turtle’s genetics can determine whether it will be bigger, shorter, or more prone to weight gain. Some genetic health conditions could affect your box turtle’s growth rate. Some box turtles might also be more prone to pyramiding, which occurs when a turtle becomes obese and their shell becomes deformed.

• Nutrition: Diet has a huge effect on the weight of your box turtle. Good nutrition can determine how well your box turtle is growing. A healthy pet turtle diet and complete nutrition support normal growth and keeps the turtle at an ideal growth rate and better body condition. A balanced diet also helps support the mental health of the turtle. Learn more in my guide on which fruits and vegetables you can feed a box turtle. You should also consider giving your box turtle calcium supplements.

• Basking: Basking also affects the growth rate of a box turtle. While basking, turtles regulate their body temperature and are exposed to UVB lights. UVB helps support Vitamin D production that activates the calcium of a box turtle’s body. This ultimately leads to the prevention of bone disease and shell rot and contributes to a better growth rate. A box turtle with an inadequate basking environment will certainly be stunted in growth.

• Health and ailment: Good health is important for the overall size of box turtles. Your adorable pet might be growing slowly or is underweight due to some illness. If your box turtle seems to be sick, the best option would be to take it to a vet. You can read my article on Pet Turtle Diseases to get a better idea of what to look out for.

If you plan on getting a box turtle, you should check out my article on the best box turtle habitat.

Growth rate: wild vs captive box turtle

Both wild and captive box turtles are the same genetically, buy you might be wondering if they are different sizes. You should know that the growth rate and size vary for wild box turtles and captive ones. The difference comes down to their diet and surroundings.

• Age and genetics work in the same way for both wild and captive box turtles.
• Wild box turtles are exposed to natural sunlight which is better than artificial bulbs.
• Wild box turtles need to hunt for food. It is tough for them to get a proper and balanced diet, and it is common for them to starve from time to time.
• Box turtles cannot grow during hibernation. Often, wild turtles have to face difficult weather conditions and they need to hibernate during winter.

Due to the reasons listed above, captive box turtles are on average usually an half inch larger than wild box turtles. Additionally, it usually takes wild box turtles a little longer to reach their full size.

To learn more about the differences between captive and wild box turtles, check out my article on how long do box turtles live in captivity?

How do I know if my box turtle is overweight?

Box turtles can become overweight if they consistently consume more calories than they expend. Box turtles often become fat if they consume excessive amounts of high-starch food or live in small tanks with little room to swim.

Sometimes, a fat turtles’ necks become so fat that they can’t even pull their heads back into their shells. Fat starts bulging out from their armpits and in front of their back legs.

The box turtle should be able to fit entirely within its shell. If not, they are a bit bulky and need to lose a few ounces. Provide them lots of space to swim and dive and offer them limited quantities of high-starch and high-calorie food.

When box turtles are out of shape and overweight, they get tired and might develop health problems.  

Wrapping It Up

To accelerate the growth rate of box turtles, you need to give them a healthy and balanced diet. Also, provide them with an ideal environment to develop and grow at a normal rate. You should ensure that the temperature and humidity of the enclosure are desirable for your box turtle.

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