Turtles are a very common type of pet, and many people tend to get attached to them due to their unique but endearing appearance. Many new pet owners usually prefer them because they are quite independent and do not require too much effort to be taken care of.

However, new pet turtle owners need to know that it is important to educate themselves first on the species, so they can be fully prepared for them by the time the turtle gets to their home.

There is a lot of important information about turtles that new pet owners need to know before adopting, but the size of their full growth is definitely at the top of the list. This is because while turtles grow very slowly, they live for many years, so many people do not realize that their tiny baby turtle might become much smaller in its later years. So, how big does a turtle get?

small turtles

Factors That Affect the Growth Rate of a Turtle

There are a large variety of factors that can affect the full size a turtle can reach throughout its life or its growth rate. Let’s take a look at the most important factors below.

The Genetics of the Turtle

Because turtles exist in such a variety in nature, it is hard to determine the standard size an average turtle can reach or its growth rate. The total growth size depends on the kind of turtle, as a lot of different turtle kinds come in all types of sizes.

For example, sea turtles come in different sizes than some land turtles or tortoises. Therefore, there are a lot of differences between certain species or sub-species. Moreover, even turtles of the same species or sub-species can differ in size. This means that genetics is a very strong variable that cannot be easily predicted.

The Turtle’s Living Habitat

There is also a difference between turtles that live in nature and the turtles that live in captivity. Turtles in captivity often live longer than those in nature and grow larger. This is because the overall living conditions for turtles in captivity tend to be better.

Turtles in captivity live in controlled environments, where the water quality and quantity are constantly monitored, a basking spot is always provided, and UV lights are programmed to be on for the exact period of time the turtle needs so to grow.

UV lights are important for turtles since it affects the growth of their bones and especially their shells. Moreover, the space of a turtle tank provides them safety from predators. However, too small of an enclosure space can also work against a turtle’s growth.


All the above are not guaranteed in nature. Clean water is not always a certainty, which can affect a turtle’s health and, thus, growth rate. Lack of UV lights can also lead to metabolic bone disease. Moreover, trying to survive in nature can also cause stress to turtles, which also affects their growth rate.


A healthy diet is another important factor impacting a turtle’s growth rate. The better a turtle is fed, the faster it will grow. Of course, a healthy diet is based not on quantity but on quality. A pet turtle owner needs to do their research to determine what foods are more appropriate for their turtle. Different kinds of turtles require different types of foods.

Moreover, the turtle’s age will also determine the appropriate food for your turtle. A schedule is also another important part of a healthy diet, so if you hope to accelerate the growth rate of your turtle, you need to get organized.

Of course, a healthy diet is another thing that is not guaranteed in nature for a wild turtle. A turtle in nature will feed when it can find food, so there is no way a steady schedule can be maintained. There may also not be sufficient natural resources available. Moreover, the type of food a turtle can scavenge is by no means the best food it can get to accelerate its growth rate.

sea turtle in the ocean


Female turtles in most species tend to be bigger than male turtles. However, the size difference is usually not too noticeable. It is also hard to determine the ratio of the size difference between males and females because sizes regularly vary, and thus, size differences also vary.

How Big Does a Sea Turtle Get?

As previously mentioned, different species or sub-species of turtles are of different sizes. This is also true for sea turtles. Let’s look at the average sea turtle sizes in the chart below.

Type of Sea TurtleAverage Sea Turtle Size
Leatherback sea turtle6 feet
Green sea turtle4.5 feet
Loggerhead sea turtle3.6 feet
Flatback sea turtle3.2 feet
Hawksbill sea turtle3 feet
Olive ridley sea turtle2.5 feet
Kemp’s ridley sea turtle2 feet

Interestingly enough, the biggest sea turtle in history—and perhaps the biggest turtle overall—was the Archelon sea turtle. This giant sea turtle, which has now become extinct as it lived millions of years ago in the Cretaceous Period, grew to sizes around 13 feet in length.

Other sea turtles grow from two-inch hatchlings to adult sizes three feet long and between 300 and 350 pounds.

The diamondback terrapin turtle prefers salt water but is not fully marine and is not a true sea turtle. However, it is another common snapping turtle. It is on the smaller side. Males typically have a shell length of 5.5 inches, while females can grow up to 11 inches long. The adult female diamondback terrapin turtle also has a larger head, wider jaw, and shorter tail.

How Big Does a Land Turtle Get?

As seen in the graph above, there is a wide range of sea turtle sizes. Let’s take a look at the average sizes of the land turtles, specifically focusing on the largest species, in the graph below.

Type of Land TurtleAverage Land Turtle Size
Galapagos Giant Tortoise4 feet
Asian Giant Softshell Turtle3.5 feet
Shanghai Softshell Turtle2.5 feet
Olive ridley sea turtle2.5 feet
Arrau Turtle2 feet
Alligator Snapping Turtle2 feet

In terms of the smaller land turtle species, the sizes are significantly smaller. Let’s look at the average sizes for the smaller kinds of land turtles in the chart below.

Type of Land TurtleAverage Land Turtle Size
Red-Eared Sliders5 – 12 inches
Western Painted Turtles4 – 10 inches
Wood Turtles9 inches
Eastern Box Turtles4 – 8 inches
Texas Map Turtles3 – 8 inches
Musk Turtles5 – 7 inches

While the largest land turtle species is considered to be the giant tortoise found in the Galapagos Islands, the largest turtle that currently exists is still the Leatherback sea turtle.

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