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How Big Do Red-Eared Sliders Get?

Compared to other North American freshwater turtles, the red-eared slider is considered to be moderately sized to large. So, how big do red-eared sliders get?

Many pet owners are curious about the size of their red-eared sliders, a popular pet turtle species. Understanding the growth patterns of these aquatic turtles can help in providing proper care.

Well, red-eared sliders reach a carapace length of about 12 inches, and this is the upper limit from an overall range length of 4 to 12 inches. Weight-wise, they can reach a mass of up to 7 pounds (3.2 kg).

Similar to other reptiles, turtles keep increasing in size throughout their lives, but the rate at which they increase drops drastically once they reach maturity. For males, this occurs between the ages of 2 and 5 years of age, while females mature between the ages of 5 and 8.

Since females reach maturity later at a later age, they tend to be much larger, but there is a little more to red-eared slider’s growth cycles that you should know about.

Red-eared slider turtles, a common sight in pet stores, are known for their distinctive yellow stripes and red patches on their heads resembling ears. These aquatic turtles thrive in environments with aquatic plants and small fish, which are essential for their diet.

The Red-Eared Slider – Species-specific info

Two wild red-eared sliders sharing a log
Red-eared sliders sharing a log

The red-eared slider is a moderately sized pond turtle that gets its common name from the red stripe on both sides of its head (around the ears), and its habit of escaping by quickly sliding into its freshwater habitat when approached.

Native to regions like the south-central United States and northern Mexico, red-eared sliders are often found in outdoor ponds and lakes, basking in the sun on logs or rocks. They play a vital role in their ecosystem, feeding on small animals and contributing to the balance of their habitats.

The red-eared slider is a subspecies of the pond slider species, and its trinomial name is Trachemys scripta elegans. Other subspecies include T. s. troostii (Cumberland slider) and the nominate subspecies –  T. s. scripta (yellow-bellied slider).

This turtle’s head is oblong with an upward-pointing snout and it also has thin, vertical lines on the limbs and neck.

Sliders have oval carapaces with sharp edges, too, while the plastron, on the other hand, is flat and smooth. The carapace is black, brown, gray, or even greenish-yellow, changing color as the turtle slowly ages. As hatchlings, the carapace is leaf green, and it turns darker green as the turtle ages.

Eventually, that dark green turns brown to olive green, but this can take many years to occur. The plastron of the red-eared slider will be light colored with dark patterns, and their skin will have a brown or dark green hue.

As an aquatic species, the feet of this turtle are webbed, an adaptation that allows the turtle to swim more easily. All of the feet have five digits and you’ll notice that Males generally have longer claws than females.

Endemic to North America, the red-eared slider’s native range includes Florida, and Virginia to Colorado. It is considered an invasive species, however, due to its popularity in the pet trade and owners releasing their turtles into the wild.

As a result, it is now found all over the world and throughout most of North America! Needless to say, the red-eared slider species is able to thrive in a wide variety of habitats.

Within their native range, they inhabit freshwater habitats such as slow-moving rivers, ponds, streams, creeks, and swamps, and they prefer to reside in warm waters. Because of their invasive nature, they have been banned in Australia and several other places around the world.

Similar to other North American pond turtles, the red-eared slider brumates when temperatures are low enough. Similar to hibernation, brumation allows the turtle to survive cold parts of the year when food is scarce.

During this time, their activity is greatly reduced, although they may stir if it warms up a little to grab a snack for more energy or to bask in the sun, returning to brumation if the temperature drops again.

This turtle brumates when temperatures fall below 50 degrees Fahrenheit (10 degrees Fahrenheit) and it is essential to keep this in mind — even captive red-eared sliders will enter brumation if the temperature within their enclosure drops enough.

In the first year of their lives, young turtles and baby turtles grow rapidly, reaching a significant portion of their maximum size. The size difference between male and female red-eared sliders becomes apparent as they approach sexual maturity, with female turtles generally growing larger.

Growth Rate

red-eared sliders in a swimming pool

The carapace length of the adult red-eared slider ranges from 3.93 to 11.41 inches (10 to 29 cm) and females are generally larger than males. The average carapace length of adult females is 10 inches (25 cm), while the average length of adult males is 7 inches (18 cm).

The growth rate of these turtles is influenced by several factors, including the quality of their living conditions. Adequate water quality in a spacious gallon tank, along with UVB lighting and a basking area, are crucial for healthy growth.

The red-eared slider can also reach a mass/weight of 3200 grams or 7 pounds.

When the turtle reaches maturity, the growth rate slows down drastically. Females reach maturity at ages 5 to 8, with carapace lengths of 5.9 to 7.877 inches (15 to 20 cm). Males mature faster, reaching maturity between 2 to 5 years of age with a carapace length ranging from 3.54 to 4.33 inches(9 to 11 cm).

Upon emerging from their eggs, hatchlings will have a carapace length of .90 to 1.37 inches(2.3 to 3.5 cm). Upon hatching, both males and females are of about the same size and length — only upon reaching maturity do females become noticeably larger than males.

The size of an adult slider can help you determine the sex of the individual and in a similar vein, the size of a subadult and juvenile can help determine the age of the individual. Since they essentially stop increasing in length upon maturity, determining the exact age of an adult is difficult.

The chart below shows the approximate growth rate of sliders.

Age (years)Female’s average Shell Length Females average Shell Length 
11.6 inches (4 cm)1.6 inches (4 cm)
22.4 inches (6 cm)2.4 inches (6 cm)
34 inches (10 cm)4 inches (10 cm)
44.5 inches (11.5 cm)4.5 inches (11.5 cm)
5-66 inches (15 cm)6 inches (15 cm)
6 to 86 inches (15 cm)8.5 inches (21.6 cm)
Over 86 inches (15 cm)9.5 inches (24.1 cm)
Red-eared Slider – Approximate growth by age

Upon hatching, hatchlings have a carapace length of .90 to 1.37 inches (2.3 to 3.5 cm). Both males and females are about the same size at this point and their overall length increases to 1.6 inches (4 cm) at age 1.

By age 2, the individual should reach a length of approximately 2.4 inches (6 cm).

By age 3, both males and females reach a length of 4 inches (10 cm). At this stage, males would have reached maturity and can reproduce. The male may still continue to increase in size, but it will be at a very slow rate, if at all.

The female is not considered reproductively mature at this age and is unable to reproduce.

At age 4, both males and females should reach a carapace length of approximately 4.5 inches (11.5 cm).

At ages 5 to 6, both males and females would have reached a length of 6 inches (15 cm). At this stage, females are considered reproductively mature, and generally by this age the males will stop growing.

Do not expect any significant increase in size – it COULD happen but any changes will be minimal. Females, on the other hand, may well continue to increase in size.

At ages 6 to 8, females may reach a length of 8.5 inches (21.6 cm), and this may increase to 9.5 inches (24.1 cm). Some females may even reach a length of 12 inches although this is rare.

If you would like to learn more about red-eared sliders and how fast they can grow, then we’ve got you covered!

Factors That Affect The Size of the Red-Eared Slider

Several factors affect the size of an individual slider. These factors include diet, age, sex, environmental conditions, and genetics, and we’ll expand a little on each in the sections below.

Pet owners should be aware that providing a balanced diet is key to the development of their pet turtles. A mix of aquatic plants, small fish, and specially formulated turtle food from pet stores ensures that red-eared sliders receive the nutrition they need.

Diet

The food and feeding schedule of the turtle has a lot to do with its size. This applies to both wild individuals and pet red-eared sliders. The diet of the species is especially essential when the individual turtle is a juvenile, as this is the time that they will grow the most.

As adults, their diet consists mostly of plants, and the microflora they develop in their digestive guts allows them to effectively and efficiently digest that plant matter and acquire the nutrients that they need.

Juveniles, on the other hand, lack this microflora, and so to acquire all the needed nourishment, juveniles need to eat large quantities of animal material. This is very important to know, as a lack of animal material in their diet can lead to stunted growth.

To promote a healthy turtle, a good filtration system and regular water changes are essential, especially when keeping red-eared sliders in an indoor or outdoor pond. These species of turtle are adaptable but thrive best with proper care.

Juveniles that have limited access to animal proteins in the wild are smaller in size, and similarly, the diet of captive individuals also affects the size of the turtle.

Individuals who are fed high-protein and high-fat diets will generally be larger but try not to overdo it — The red-eared slider can even end up obese when fed too much protein and fat!

In the wild, juveniles feed on small prey such as fish, snails, slugs, amphibians, clams, and even small reptiles.  Plants they feed on include aquatic vegetation and terrestrial vegetation, with leaves, stems, and roots bein common parts of their diet.

For optimal growth, be sure to offer your juveniles proteins, and plant materials.

Some animal proteins to offer include feeder fish, insects such as catepillars& worms, shrimps, and commercial aquatic turtle diets. Offer plant material such as freshwater plants such as water lilies, leafy greens such as romaine lettuce, and grass such as alfalfa grass.

Is your red-ear slider not eating? Don’t worry – we can help!

The transition from juvenile turtles to adult turtles is marked by a slow-down in growth rate after they reach sexual maturity. The size of a red-eared slider also depends on whether they are wild or captive, with pet releases often growing to a larger size due to better living conditions.

Age

As mentioned earlier – the older the turtle, the bigger it will be, and with younger turtles, you can even use the size to estimate their age. Hatchlings are smaller than 1.6 inches in carapace length and within the next two years, they reach a carapace length of 2.4 inches.

They continue to increase in size until maturity, at which time you will no longer be able to estimate their age by size, but with hatchlings and juveniles, the size will give you a pretty accurate estimation.

Sex

The distinct size difference between male and female turtles is a fascinating aspect of these native turtles. While the male red-eared sliders are smaller, the female red-eared sliders can be quite impressive in size, often sought after by pet owners for their striking appearance.

The sex (gender) plays a major role in its final size. Simply put, adult females are larger than adult males by several inches. While the average adult carapace length of males is 7 inches (18 cm), the average adult carapace length of females is 10 inches (25.4 cm). In fact, some females can reach a length of 11.81 inches (30 cm).

Males and females are of similar sizes growing up. However, females reach maturity at a later age. While males stop growing in length at age 5, females will continue to grow until they are 8 years old. Those extra three years definitely count, as the females will be much bigger than the males.

To maintain their health, red-eared sliders require a habitat with deep water, land area, and basking spots. The use of UVB bulbs in their enclosures plays a critical role in their overall well-being.

Environmental Conditions

red-eared slider kept in a temple pool

For the individual to reach a healthy size, the environmental conditions have to be just right. This is particularly true of pets. These environmental conditions include lighting, heating, and clean water.

Red-eared sliders, like the painted turtle and other native species, are resilient and can adapt to various water temperatures. However, to reach their maximum size, they need enough water and a land area to regulate their body temperature.

The water temperature should be 75 to 80 degrees Fahrenheit, and many owners prefer to keep the water temperature between 70 to 75 degrees. As long as the water temperature isn’t below 60 degrees Fahrenheit, the turtle should be okay, but 70 – 75 degrees is the ‘sweet spot’ for sliders.

When temperatures are low enough, the turtle will enter brumation mode. At this point, the turtle will stop feeding. During brumation, the turtle loses a lot of weight and does not increase in size, so be sure to use a thermometer or thermometer sticker to keep a close eye on the temperatures.

The temperature of the turtles basking spot should be a bit warmer, with 84 to 94 degrees Fahrenheit being ideal.

The tank size is also important. A tank size of 50 gallons minimum is required and you should have 10 gallons per inch of length of each turtle in the tank. Keep the water within the tank well-filtered by installing a powerful filter pump, as red-eared sliders can be a little messy.

LafeberVet has some more information on this and other useful red-eared slider facts and you can find it here if you would like to learn more!

If you feel like something is missing from your turtle’s environment, then be sure to check out our Red-eared slider turtle tank setup guide when you’re done here – you’ll be happy that you did!

Genetics

Some individuals will be naturally large and some will be naturally small. Just like humans, genetics go a long way in determining the size of the individual turtle, so two turtles fed and housed the same might be very different in size and that’s OKAY.

Just be sure they are getting enough proteins and plants and let nature do the rest!

Frequently Asked Questions

How long does it take for a red-eared slider to reach full size?

The red-eared slider reaches full size between the ages of 2 to 8, depending on their gender. Males reach maturity earlier, between the ages of 2 and 5, and take less time to reach their full size.

Females take longer to reach maturity, becoming mature between 5 and 8 years old, and thus take more time time to reach their full size.

How big can a female red-eared slider get?

Females can reach a length of about 12 inches or 30 cm and may reach a mass/weight of up to 7 pounds (3.2 kg), although most females will average 10 inches in length.

How big do male red-eared sliders get?

The average length of adult males is 7 inches (18 cm) and they should reach this size between the ages of 2 and 5, when the male will be considered mature. The male may grow a little more after reaching maturity, but if so, it will be very minimal.

How long does a red-eared slider live?

Red-eared sliders are hardy little turtles, with a lifespan of approximately 30 years in the wild and 41.3 years in captivity, but there are certainly exceptions. One of the oldest is a 65-year-old slider named Magoo.

Conclusion

Understanding the growth patterns and needs of red-eared sliders, from the baby turtle stage to old individuals, is essential for anyone looking to keep these turtles as pets. A field guide or advice from experienced pet stores can provide valuable information on caring for these fascinating creatures.

Compared to other North American pond turtles, the red-eared slider is considered ‘medium-sized to large’. Mature males have an average carapace length of 7 inches (18 cm) and females tend to be 10 inches (25 cm) in length, with rare exceptions.

Adult females are generally larger than adult males because they take a longer time to reach maturity and red-eared sliders do most of their growing before they mature. Even after maturity, however, they may continue to grow but the increase will be fairly insignificant.

The upper limit on the size of these turtles is 12 inches (30 cm) and 7 pounds (3.2 kg) and their large size and adaptability have made them one of the most invasive species on earth.

Thankfully, they are also some of the most fantastic and beautiful turtles to host at home!

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