How Big Do Red Eared Sliders Get? (Detailed Guide)

A red-eared slider turtle, also known as the Singaporean turtle, is a sociable pet turtle characterized by attractive yellow and green markings and red patches behind their eyes.  Their unique pattern, small size, docile personality, and longer lifespan makes them a great addition to any home. If you are contemplating adopting a red-eared turtle? It’s important to know how big the pet turtle gets to consider the requirements such as diet and tank size.

So, how big do red eared sliders get?

Red eared sliders can grow to 12 inches in length and weigh up to 6 pounds. However, the size and weight of the turtle can differ based on several factors such as Age, Diet, Habitat, Gender, Genetics, and UV light.

Let’s take a closer look at these factors and how they influence how big a red eared slider can get.

Picture of red eared slider turtle
Copyright: mariedaloia

Factors That Influence How Big Red Eared Sliders Get

1. Age

Like other turtles, red-eared sliders start as eggs. The difference is they are tiny, usually 1 inch in length.

As a result, the hatchlings are very small, but the change happens quickly once they hatch. In fact, you will notice that the red eared sliders will grow fast within the first weeks.

The rapid growth keeps on to about 2 – 4 years and then begins to slow down.

A juvenile red eared slider is about 2 inches in a few months. Then, the turtle takes about a year to grow another inch.

Age is an important factor in the natural habitat because the older a turtle gets, the bigger it gets. The bigger it gets, the fewer the predators.

For example, the Galapagos are some of the biggest turtle species in the aquatic world, making them too big for predators to hurt them.

So, after they reach a certain size, minimal effort is needed to grow because they can search for food without worrying about anything hurting them.

The same principle works for red eared sliders. As they get bigger, very few animals can hurt them. This allows them to feed and survive and become bigger.

When kept as pets, ensure to feed a young red eared slider more proteins than the adults to support their rapid growth.

2. Gender

Gender is also a determinant for a turtle’s growth potential. Generally, females red eared sliders are known to be larger than males because they carry eggs inside their bodies.

Since they lack a flexible body, more space is needed to hold the legs without breaking them during pregnancy.

As hatchlings, the size may not be noticeable, but as they age, the difference will be clear.

3. UVB Light

UVB is a light spectrum of UV light that is beneficial to most reptiles, including turtles. This light offers Vitamin D3, which helps the turtle to retain calcium in the body.

Without UVB light, the turtle could suffer calcium deficiency, leading to improper shell and bone growth.

Turtles in the wild obtain UVB from basking, so they need to look for a place with sufficient sunlight.

They do so by climbing on big rocks and other places closer to the sun. Red eared sliders are known to lay in the sun for hours to expose the shells to the UVB rays.

In an artificial environment, you should equip their areas with a UVB bulb to replicate the effect of UVB rays from sunlight.

Turtles that get sufficient UVB will grow much faster than those who don’t have sufficient access.

Having UVB lighting in the tank of your red-eared turtle can contribute to significant growth. Turtles without UVB light tend to grow slower than usual.

4. Diet

The diet is another important factor that determines the size of your red eared slider turtle. Keep in mind that slider turtles are omnivores, so you need a mix of plant-based foods and meats.

Some of the ingredients to have in your red-eared slider’s diet include:

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

Vegetables and other plants offer your turtle a wide variety of vitamins to fight off illnesses and stay healthy. Vegetables should form a big part of your red-eared slider’s diet as it attains maturity.

Dark leafy greens like romaine lettuce, kale, mustard greens, collard greens, and bell pepper are recommended. However, they do not offer enough nutrition for your turtle to grow.

As a result, you need to have more protein for your slider, including meats, as these are directly responsible for the growth of red-eared slider turtles.

Insects and other small animals are tasty for turtles, contain little fat, and are tasty for turtles.

Very young red-eared turtles are predominantly carnivorous and will need more protein to grow faster.

It’s perhaps the main reason you should feed your baby turtles enough worms, crickets, krill, and shrimp to help them maximize their growth.

Still, you need to avoid too much of protein to avoid pyramiding. Simply put, pyramiding is when your turtle’s scutes grow and cause a dome shape.

The good thing is pyramiding rarely occurs, and when it does, it’s not as dangerous unless it’s more pronounced.

Excessive pyramiding can go deeper than the shell and interfere with the turtles’ lungs causing breathing difficulties.

Besides, female turtles with this condition may have problems laying eggs. Pyramiding also adds to the turtle’s weight, which can make the legs weak and cause joint issues.

The condition is more common in tortoises than aquatic turtles but can still happen for the red eared slider. If your turtles are affected by this problem, you need to adjust the diet and reduce protein content.

Overall, turtles will still grow even if they don’t have a proper diet, but not at a normal rate.

A red-eared slider’s proper diet needs to have enough meat for protein, as well as veggies and fruits for vitamins and other nutrients. Turtle pellets offer calcium and other nutrients your turtle needs.

Make sure to provide the turtle with different foods so that it doesn’t lose appetite. If you are unsure about the proper diet plan for your red-eared slider, you should consult a vet to get a diet chart for red-eared turtles.

5. Supplements

Some supplements also offer specific nutrition needed by turtles for growth. The supplement includes Vitamin A and D3 and, of course, calcium.

A turtle’s bones and shell depend on calcium which is literary the blocks building your turtle’s personal home.

The more supply of calcium vitamin supplements for your turtle, the speedier the growth. You can add the supplement in the tank water where the shell can absorb the calcium while swimming.

A cuttlebone can also be a good supplement for your turtle to give them some more calcium. This is a white chalky substance to give your turtle to munch on. Just ensure to remove the hard backing for small turtles to prevent choking.

The good thing with supplements is they provide more nutrients not contained in the foods. They can accelerate a turtle’s growth so it can reach its growth potential much quicker.

However, avoid providing more than the required amounts as too much of everything is bad.

On the other hand, a lack of calcium can cause the turtle to become sick, possibly death.

6. Space

The available space in the tank can also determine the size of a red-eared slider. Having an aquarium that’s big enough for your turtle can help him exercise and achieve his full growth potential.

The ideal tank size of your red-eared slider should be at least 5 times the size of the turtle. Remember that red-eared sliders love to swim, so they can really benefit from having a bigger tank.

As for baby sliders, you can provide a 30-gallon tank before it develops into a juvenile turtle.

A juvenile needs at least a 55-gallon tank because it measures about 6 cm. a fully grown turtle is about 11 inches, so the aquarium should be about 125 gallons.

Having a bigger tank is also necessary to ease the workload of your filtration system, as turtles can get quite messy. Keep the aquarium clean can prevent infections caused by bacteria and salmonella.

7. Genetics

While you can influence the growth of your turtle by offering a balanced diet, UVB light, and other favorites, but the growth will be determined by something you cannot control, their genetics.

How big and fast the slider can get is partially determined by who the parents were and the species.

While you should put the best effort into offering them basic needs like a tank and a good basking spot, you can’t exceed the growth limits.

Many pet owners may force the turtle to overfeed to try and grow super turtles. It’s unnecessary because this will hurt the turtle and may end up suffering pyramiding and obesity.

Sliders will do a great deal of growth in the first stages of life, growing up to 4 inches. After this, your turtle will grow an inch every year until its genetic maximum at age eight or so.

Are Pet Red Eared Turtles Different from the Wild Turtles?

It depends, but pet turtles tend to be bigger than wild sliders due to access to better conditions. If you provide the right conditions for your red-eared turtle, then it should definitely grow bigger than those in the wild.

Wild turtles usually lack enough food, and the weather may not always provide enough UVB rays and the constant threat from predators.

Unlike pet turtles, there’s one more major challenge that wild turtles have to deal with – the winter.

Wild turtles have to hibernate during the cold season to avoid the bad weather. During hibernation, they may spend too much energy, calcium, and proteins to see to the next favorable weather.

On the other hand, pet turtles have access to UVB bulbs and have enough food supply to grow.

If wild turtles didn’t have to hibernate, they could use the resources to grow, not to survive the harsh climate.

Basically, every pet turtle has 12 months of UVB access compared to just 8 months for wild turtles.

What to Feed a Red-Eared Slider?

In the wild, turtles feed on aquatic vegetation, tadpoles, fish, and invertebrates. Sliders boast a sharp ridged beak that can tear up prey and cut veggies into small pieces.

Adults should feed 20% protein probably twice or thrice per week, and green should be offered every day. Juveniles should get 70% protein, ideally five days a week, and allow them to graze on greens.

Check out examples of foods for a red-eared slider:

  • Leafy greens – Kale, Romaine lettuce, mustard greens, collard greens, dandelion greens, water lettuce, peas, spinach, red leaf lettuce
  • Vegetables – Sweet potato, carrots, broccoli, green beans, squash
  • Protein – boiled meat, poultry, chicken, frozen bloodworms, earthworms, mealworms, krill, feeder fish, pinkie mice
  • Fruits – pears, berries, apples, melon

You should avoid certain foods such as raw or processed meats, avocadoes, onions, and chocolates.

Avoid fatty fish species the likes of goldfish and go for captive-bred fish. Frozen fish may contain toxic levels of enzymes, and wild ones may carry parasites.

Be cautious with fruits because they may contain too much sugar that could cause diarrhea in turtles.

Make sure to include a multivitamin to supply calcium, vitamin D3 and other nutrients. Turtle food is also recommended but should not exceed 25% of their diet.

What Should Baby Red-Eared Sliders Eat?

Although a baby red-eared slider is omnivorous, its diet should be primarily proteins.

The best way to ensure they get enough nutrition for faster growth is by offering them a good turtle pellet as a staple food.

If possible, you can also have other meat and insect sources to supplement the pellets.

Any of these insects and animals will do:

  • Earthworms
  • Mealworms
  • Bloodworms
  • Dried shrimp
  • Crickets
  • Small fish

If your baby red-eared slider is under 2 inches in length, it needs to be fed every day. Feed them enough food, which would be roughly the size of their head.

This is about a level tablespoon of food, including small fish, mealworms, and other food.

Ensure you feed them as much as they can in 5 minutes but don’t let them eat for more than 10 minutes to avoid overfeeding.

Why Is My Baby Red-Eared Slider Not Eating?

It is common for red-eared sliders hatchlings to refuse food in the initial days after getting them.

But first things first – avoid feeding it plant-based foods as they probably won’t eat them. Remember that most baby turtles prefer proteins in their natural environment for rapid growth.

So, it’s highly likely that your baby slider doesn’t want your vegetables, especially if they still taste protein foods.

“What if my baby red-eared slider won’t eat proteins as well?”

A baby red-eared slider turtle won’t eat because of stress caused by being moved into a new habitat or aquarium.

 As it ages, you’ll need to provide them some leafy greens to balance out the diet.

Eventually, proteins will be less, probably once or twice a week. Also, it may be the type of food you are feeding them.

Check out these tips if your baby slider won’t eat at all;

  1. It may be caused by the food you are providing. Turtles need a variety, so you can try other food sources, such as small fish, shrimp, meals, worms, crickets, and more. Some turtles can be extremely picky eaters.
  2. The baby red-eared slider may be sick, so you can check for common illnesses and offer the right diagnoses.
  3. Check the aquarium for causes of continual stress. Consider moving the turtle away from high-traffic areas, adjust the temperature, UV light, increase space and more
  4. Be patient – turtles may need more time to adjust to a new environment. However, it should eat within a week. If they still don’t eat, check with your vet for further advice.

How Fast Do Red-Eared Slider Turtles Grow?

Red-eared sliders hatchlings will grow enormously in size during the first four years of life. They are about 1 inch in diameter during the first three months of life and weigh less than 60 grams. Expect them to expand to about 1.6 inches within the first year alone.

At age 2, they can grow to about 2.3 inches or 6 cm. Things could move even faster in year three as the red-eared slider could reach the length of 4 inches.

At age 4 to 5 years, male sliders should reach 4.5, and female sliders typically reach 6 inches.

Juvenile red-eared sliders at the age of 4 years still have a long time to mature, but they are generally mature enough to breed at this age.

They will continue growing at a steady rate of about 1 to 1.5 inches a year until they become adults.

Red-eared sliders normally stop growing in length at the age of eight. The length is about 7 to 10 inches for males and 10 – 12 inches for females. Their growth rate may vary by usually an inch.

When Are Red-Eared Sliders Fully Grown?

Sliders are fully grown at 8 years, the age at which they achieve their maximum size. During adulthood, red-eared sliders grow at a much slower pace.

Female red sliders can grow much bigger than males, normally 8-10 inches for males and 12 inches for females.

A fully mature female red-eared slider weighs about 550 grams while males do not exceed 300 grams.

Red Eared Slider Growth Chart

As we discussed before, a red turtle’s growth is rapid in its early life. Keep in mind that many variables come to play in the growth, so your turtle might not have the same growth.

The table below will give you a clear idea of the size to expect your slider to have at a certain age.

AGESIZE (length)
1 to 3 months1 inch
1 year1.5 inches
2 years2.3 inches
3 years4 inches
4 years6 inches
5 years7 – 8 inches
6 years9 – 10 inches
7 years10 – 11 inches
8 years11 – 12 inches
Red Eared Slider Growth Chart

How to Measure Your Red-Eared Slider?

When people ask about the size of the turtle, it’s the length of the shell in inches. It’s basically the straight distance across the shell.

The distance of the shell’s curve is just a straight length, so it’s barely counted. It’s just the straight length of the plastron (lower part).

Wondering how you can measure the shell growth of your red-eared slider? It’s important for you to plan their requirements.

Check out the steps below to do this successfully. Be gentle with your turtle when doing this, and avoid flipping them over and over.

  • Place the turtle upside down gently, although this might make it upset. As such, be fast to avoid keeping them like this for too long.
  • With a measuring tape, measure from end to end of the turtle
  • Measure from the plastron’s end of the tail to the end near the head.
  • Jot down the measurement in a chart or notebook. Ensure you do this regularly (monthly) to construct a chart of turtle’s growth from the recorded data.
Photo of red eared slider turtle

What Tank Size to Use for Your Red Eared Slider Turtle?

Red-eared sliders can grow relatively large. A male slider grows up to 10 inches, and females as large as 12 inches.

They start out as tiny cute hatchlings, but they are growing and will be much bigger with time. All you need is to offer them with the right tank size for the turtle size.

A rule of thumb is to measure the shell and ensure you have about 10 gallons of tank size for every inch.

This means if your red-eared slider’s shell is 2 inches long, you should have at least a 20 gallons water tank.

If the shell measures 4 inches, the tank needs to be at least 20 gallons. Now, when the turtle reaches maturity at 10 -12 inches, the tank will be somewhere 80 – 120 gallons.

Well, these might be some large-sized tanks, so appropriate preparations are needed for it.

If the tank is a bit too small for your turtle, it can leave the turtle susceptible to infections and might make it harder to clean the water.

Final Words

How big your red-eared turtle will get depends on several factors, including age, diet, aquarium tank, etc.

If you want to ensure your red-eared slider will attain its growth potential, pay close attention to all the factors discussed in this guide.

Additionally, test and observe to see what’s working for your red-eared slider and what doesn’t.

If you have been thinking of keeping turtles, we do hope that our guide on how big the red eared slider can get will help you make an informed decision regarding whether or not to keep one as a pet.

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