How Big Do Box Turtles Get? 

Written by Emmanuel Kingsley
Published: March 21, 2022
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Box turtles are solitary creatures marked by spots and splashes of yellow shells. This turtle species is a land turtle, although they love to live close to the water. Their sizes differ depending on the species and their age.

Like most turtles, box turtles live long lives doing very little except eating, mating, and sleeping. This piece explores where they come from and their lifespan. We’ll also talk about how big box turtles get at different stages and their lifestyle as pets. Then, we’ll review ways to help pet turtles reach their full size. 

Where Do Box Turtles Come From?

Box Turtles are reptiles that can be found in Mexico and the central, southern, and eastern parts of the United States. Their name comes from their ability to seal off their entire bodies in their shell – like a closed box. There are six main species: Common, Mexican, Coahuila, Spotted, Western, and Yucatan. There are also other subspecies. They all share typical features like four legs, dark brown or black shells, and the ability to completely retract their bodies into their shell. 

The differences appear in their respective sizes, shades of shell color, and the patterns of the yellow splashes. They generally like to live in warm, sheltered places. So, you may find them in hollow forest trees, marshy areas, and meadows. Any site that gives it close proximity to water supply, vegetation, and shelter is suitable for a box turtle.

How Big are Baby Box Turtles? 

Tiny Box Turtle crawling around on grass.

Baby box turtles are 1 to 2 inches long and can weigh around 0.1 pounds.

©Karen Culp/

Baby box turtles measure about 1 to 2 inches (3cm) in length and weigh about 0.1 pounds (25g). 

Box turtles lay their eggs in muddy areas. The babies, called hatchlings, hatch from the eggs in 6 to 8 weeks. Afterward, they explore out of the nest to fend for themselves. These hatchlings have tender shells and can easily be trampled under feet or eaten by turtle predators like raccoons, birds, and dogs. 

As hatchlings grow older, their shells also increase to accommodate the size of their bodies. The average length of 6-month old turtle shells is 2 inches. They grow rapidly in the first years compared to their later years. Even though turtles are omnivores, hatchlings prefer meat over other foods. So, they will eat more insects and worms and the occasional plant. 

How Big is an Adult Box Turtle? 

Box Turtle (Terrapene carolina) walking on grass.

Box turtles are 4 to 6 inches long and weigh between 0.5 to 2 pounds.

©Elizabeth Spencer/

Adult box turtles grow to 4 to 6 inches (10 to 20cm) and weigh between 0. 5 and 2 pounds (0.2 – 0.9kg).

These sizes vary depending on the species. For example, Eastern turtles measure between 4.5 and 6 inches, while Gulf Coast turtles can measure 8 inches in length. Western box turtles are typically smaller and can grow up to just 5 inches in adulthood. Their shells also grow much larger and heavier. 

From their sixth month to their fifth or sixth year, hatchlings grow into adults. On average, they reach sexual maturity in five years. Adults begin mating in the spring of their fifth year, and males compete to get female partners. 

A female adult can store sperm in her body for as long as 4 years. So, it’s not uncommon for females to lay eggs 3 to 4 years after mating. After that, they often lay three or four eggs, although there are records of adults who laid eleven eggs at a go. 

How Large Can a Box Turtle Grow? 

Box Turtle crossing the road.

Box turtles, like the Gulf Coast box turtle, can grow as long as 8.5 inches.

©Lisa Holder/

The largest box turtle species is the Gulf Coast box turtle. This turtle is a subspecies of the Common box turtle and is known to grow as long as 8.5 inches. Like their name, these reptiles are native to the Gulf of Mexico. 

They love to be around water and can be found in marshy areas or swamps. Their shells are dark-colored, typically black or brown.

Since they are larger, they face less intimidation from predators than the smaller species. And this contributes to their lifespan as they are the oldest living box turtles. Some of them have lived up to a hundred years in the wild.

How Long Does it Take for a Box Turtle to Reach its Full Size? 

Most box turtles become fully grown in seven to ten years. During this period, their shells harden, and once they reach full adulthood, they stop growing. A turtle’s growth rate depends on its species, sex, and nutrition. 

Their average lifespan is 40-50 years, although some have lived as long as 100 years. Since they attain their full size within the first ten years, their weight remains the same until the end of their days. Moreover, factors like changing habitats or poor feeding can cause them to lose weight. 

Are Box Turtles Good Pets? 

Box turtles can serve as good pets if they receive adequate care. They need warm enclosures with constant access to clean water and nutrient-rich diets. So, although it’s okay to have them as pets, they are best left in their natural habitats. 

Can Box Turtles Live in Water?

Box turtles live mainly on land, although they must stay close to a water source. Females sometimes go into the waters to lay their eggs. Others may take a swim now and then in shallow waters or ponds. They aren’t fully aquatic, so they cannot cope in deep ends of water. 

Water is essential for all turtles. These turtles, in particular, need constant access to drink, swim or soak their bodies in. It also aids their food digestion. If you own one, ensure that its enclosure has enough water for it to drink and occasionally submerge itself in. 

The photo featured at the top of this post is ©

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