How Big Do Box Turtles Get? | Do Box Turtles Stay Small?

Box turtles are small-sized turtles that require you to replicate the wild environment indoors if you want to adopt them as pets. If you plan to be a box turtle keeper, you might want to clear your thoughts on “how big do box turtles get”, right? With proper care and attention, they can easily reach 5 to 7 inches in size and 2 to 3 pounds of weight. 

What factors determine box turtle size?

The size and weight of box turtles vary from individual to individual due to various factors. Unlike humans and animals, female box turtles are larger in size as compared to male box turtles. Apart from that, box turtle growth depends on the following factors:


When box turtles hatch from their eggs, they are between 1 to 1 ½ inches in length. From this, you can infer that baby box turtles are tiny creatures, but they grow big with the passage of time. They proliferate during the initial 2 to 4 years of their life, and it slows down considerably.

Box turtle will grow from 1 inch to 2 to 3 inches in a short span, but as it grows old, it grows by 1 inch after 12 to 18 months. Wild box turtles grow bigger than their captivative counterparts due to their natural habitat. They overgrow to protect them from predators who are always in the mood to hunt them down.

Diet & Nutrition

Box turtles fall in the omnivorous category, which means you can feed them on both plant and animal-based food. Their diet includes the following stuff:

  • Turtle pellets
  • Meat
  • Fish
  • Worms 
  • Insects
  • Vegetables
  • Fruits
  • Berries

Vegetables, fruits, and berries are loaded with vitamins and minerals required by a box turtle to remain healthy. These food items are not a good source of protein needed for growth and maintenance. If you want your box turtle size to be pertinent, include meat, insects, and fish in their diet. 

Never feed your turtle with an overloaded protein diet, as it can lead to pyramiding. In this state, the individual scutes of the box turtle will grow more than the average shell level, and it looks like a pyramid. If your turtle shows signs of pyramiding, change its diet to low-protein food for some time.


The size of female box turtles tends to be a bit bigger than their male counterparts. Normally, they are ½ to 1 inch large in size as compared to male box turtles. Female bellies do not expand during pregnancy because turtles are not flexible as they need to hold their eggs inside their bodies. Therefore, their bodies are slightly bigger than males.

UVB Light

UVB light is a light spectrum of UV light. It plays a prominent role in the growth of box turtles as it gives them the vitamin D needed for the absorption of calcium. Without proper absorption of calcium, turtle’s bones and shells do not grow at the required rate. 

Wild box turtles get UVB light through basking. Simply put, basking is a way to get more sunlight by finding a suitable spot where sunlight is maximum. In the wild, box turtles uncover a place near the sun and lay there for hours to get natural vitamin D. 

Similarly, pet have basking areas where UVB bulbs are equipped to replicate the sunlight. Whenever turtles need vitamin D, they move to the basking area within the enclosure and stay there for as long as they want. Those turtles who do not get UVB rays remain small as their bodies do not grow well due to vitamin D deficiency.


Pet box turtles grow better than wild ones because they have access to diet and conditions, helping them to expand in size. Whereas wild box turtles are always in a state of survival, they have to search for food and areas where they can live. They are constantly in a situation under threat from predators. 

Pets usually do not bear the extreme winter season because box enclosures are laden with heaters, UVB bulbs, and night lamps for turtles. On the other hand, wild box turtles hibernate to survive, and during this period, they consume the fat, vitamins, and nutrients stored within their body. They remain in the hibernation period until the winter season goes off. 

During hibernation, they rarely eat, drink, and move. Along with that, wild turtles do not get UVB light while hibernating, so they are less likely to grow in this period. From this, you can reckon that pet box turtles get 12 months a year to grow, whereas wild box turtles get only 7 to 9 months at the same time.

How long does it take for a box turtle to grow full size?

In 7 to 10 years, box turtles reach their full size and grow to maximum. Their shells become hard in this period, and after that, their growth stops. Species, sex, and nutrition are some factor that determines how fast a box turtle grow.

On average, they live 30 to 40 years, but some can last up to 100 years as a box turtle max size is achieved during the initial ten years of their life. So their weight remains the same for the rest of life. They can lose weight in the end years due to changes in habitat and diet routine.

Box Turtle Growth Chart

Below is the box turtle size chart. Let’s have a look:

AgeAverage Size 
Hatching1″ to 2.”
1 Year Old2″ to 3.”
2 Year Old3″ to 3.5.”
3 Year Old 3.5″ to 4.”
4 to 7 Year Old5″ to 7.” 

From this table, you see box turtle size by age, and it shows that they reach their full size in 4 to 7 years. 

Largest Box Turtle Pics:

Frequently Asked Questions (FAQs)

How big are baby box turtles?

Baby box turtles just hatched from eggs are 1 to 2 inches in size. They weigh around 25 to 30 grams (0.1 to 0.12 pounds), making them tiny creatures.

How big are adult box turtles?

Adult box turtles, given a proper diet and living environment, can easily reach 5 to 7 inches in size. On average, they weigh between 0.5 to 2 pounds.

How big can a eastern box turtle get?

Easter box turtle is a subspecies within the box turtle genus, and they can grow as much as 5 to 6 inches. On average, they weigh around  2 to 2 ½ pounds and grow bigger than other subspecies in their genus. 

Final Words

Give your box turtle a nutritious and well-balanced diet along with a suitable living environment if you want it to grow full. An ideal indoor habitat can be a replica of wilds where a turtle gets desirable humidity and temperature. If you pay heed to the housing and diet, then I am sure your pet will grow to its optimal size.

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Hey, I've done my Ph.D. in Marine Biology. I'm a turtle enthusiast and have been owning turtles for the last 22 years and dedicated to sharing my experience to help you in pet turtle upbringing.