How Big Can Turtles Get?

A turtle’s size is greatly dependent on the species. According to research, there are 365 well-known species. However, a majority of aquatic turtles are between four to twelve inches. The weight also differs from one turtle to another. Having a proper turtle environment boosts growth. Other sizes and weight determining factors include age, habitat, provision of UV light, and gender. 

Turtles also grow very slowly. This slow growth allows them to thrive by eating the right foods under the best conditions. That said, finding out how large your turtle will grow helps set up the best habitat for it before you adopt it. 

Pet turtles have a greater chance of maturing faster because of readily available food and excellent living conditions. So, it’s best to equip yourself with enough information about your new pet, as you’ll find below. 

How big can a pet turtle get? 

How big can turtles get?

A pet turtle can grow up to twelve inches long. However, if you take home a red-eared slider turtle, it won’t grow to the same size and weight as a wood turtle. The turtle species, age, gender, and habitat play a significant role in the growth of a turtle. So, it depends on how well you care for your pet. 

Pet turtles receive extra care by getting balanced diets, UVB light, and the perfect water temperature. As such, they grow bigger than turtles in the wild that face predation and food scarcity. Factors that affect the size of a pet include: 


Naturally, some turtle species grow bigger than others. Species like the red-eared slider turtles grow larger than box turtles. Moreover, features like the turtle’s carapace (the top side of the shell) differ from one species to another. The shell makes a turtle appear larger or smaller depending on its size or shape. 

For instance, red-eared slider turtles are between nine to twelve inches long. They are currently the largest aquatic turtles found in many aquariums. On the other hand, box turtles are about five to six inches long. Indisputably, they are significantly smaller in size than red-eared sliders. 


Baby turtles are much smaller than adults. Although environmental conditions cause some turtles to stagnate, younger turtles are tinier. As a result, a baby turtle cannot weigh the same as an adult.

Snapping turtles are 2.5 inches long and weigh a few ounces as hatchlings. However, adult snapping turtles go up to 9.4 inches long and weigh 35 pounds.  

Tank Size 

You should determine the appropriate tank size after knowing the turtle’s full length and weight as an adult. Although turtles look small initially, they grow larger (though slowly). Therefore, add ten gallons of water to the tank for every inch of your turtle’s length. 

Getting smaller tanks limits the turtle’s movement. In no time, the lack of space will also limit the turtle’s growth. Similarly, most turtles need a basking dock. If you don’t provide that, the turtle won’t bask or rest, which is detrimental to its health. 


Turtles need more than a balanced diet. They are aquatic and terrestrial animals. Thus, they need optimal water temperature between 72 to 82°F and availability of UVB light. Since turtles love basking, offering heated lamps maximizes their chances of healthy growth. 

Turtles in the wild have to deal with food scarcity, predators, and inconsistent water temperatures. Such factors make them smaller than domesticated turtles.  


Male and female turtles are about the same size and weight until they reach maturity. Then, females grow much bigger in size and weight. Although the turtle species also play a role in this, most species have females with large shells to accommodate many egg clutches. 

Males need to be lighter and more agile for swimming due to reproduction. Their flat shells allow proper limb movement for swimming. 

What’s the average size of a full-grown Turtle?

Adult turtles weigh differently if they don’t fall under the same species or gender. The largest full-grown aquatic turtle is twelve inches long. If a turtle grows in captivity, it is more likely to develop more than one in the wild because of better conditions. 

Moreover, turtle species have differently-sized features, like the carapace, distinguishing them size-wise. 

Below is a table showing average sizes for common aquatic species: 

Turtle Species Average Size 
Red-eared sliders 9 to 12 inches 
Western painted turtles 6 to 10 inches 
Wood turtles 7.8 to 9.2 inches 
Eastern box turtle 5 to 6 inches 
Texas map turtle 4 to 8 inches 

What is the difference between male and female turtle size

While young, male and female turtles are similar in size making them difficult to differentiate. However, as noted above, you’ll notice the difference when they are ready to reproduce. Female turtles grow larger as they start egg production at six to seven inches long (depending on the species). 

Males, on the other hand, are smaller for purposes of copulation. In addition, their tails are longer and thicker than the females’ to protect the cloaca. 

Here’s a list of differences in male and female sizes according to species. 

Turtle Species Male Size Female Size 
Red-eared sliders 8 to 9 inches 10 to 12 inches 
Western painted turtles 5 to 6 inches 8 to 10 inches 
Wood turtles 8 to 9.2 inches 6 to 7.8 inches 
Eastern box turtle 4 to 5 inches 5 to 6 inches 
Texas map turtle 2.5 to 4 inches 5 to 8 inches 

What is the largest Turtle to ever live?

The largest turtle documented to ever live is the Archelon. The turtle lived approximately 70 million years ago. Archelon went extinct due to increased predation of eggs and hatchlings. According to historical information, the turtle had unique features compared to modern-day species. It weighed 5,000 pounds, and measured 16.4 feet from head to tail and 16 feet from flipper to flipper. 

Since then, other turtle species have faced extinction. These include the leatherback, loggerhead, Kemp’s ridley, and hawksbill. Despite the challenges, these turtle species still exist in modern times. Still, they are not as large as their ancestors. They weigh as follows:

  • Kemp’s ridley – 27 to 32 inches at approximately 100 pounds 
  • Leatherback – 6.5 feet at approximately 1500 pounds 
  • Hawksbill – 2 to 3 feet at 150 pounds 
  • Loggerhead – 2.3 to 3.5 feet at about 375 pounds 

How Much do Turtles weigh?

Some sea turtle species, like the leatherback, can weigh up to 1500 pounds. However, domesticated turtle species range between two to seven pounds. This weight depends on the turtle’s species, gender, and age. Typically, female turtles are larger and heavier than males. Baby turtles weigh approximately two pounds, with some species weighing less than that. 

The reason for the weight difference between male and female turtles is the ease of reproduction. Males are lighter with flatter shells. These features enable them to swim easier to find mates during the mating season. On the other hand, female turtles must be heavier to withstand the reproduction process. 

Additionally, female turtles have larger domed shells to create enough space for large egg clutches. More eggs mean more hatchlings, thus a higher chance of survival for the turtle species. 

Here’s a table showing differences in weight according to sex and turtle species:

Turtle Species Male Weight Female Weight 
Red-eared sliders Less than 4 lbs Up to 7 lbs 
Western painted turtles About 0.7 lbs Up to 1.1 lbs 
Wood turtles Up to 1.5 lbs Up to 2.5 lbs 
Eastern box turtle About 1 lbs Up to 2 lbs 
Texas map turtle Up to 0.9 lbs Up to 5.5 lbs 


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