There are many reasons you might want to know the age of a red-eared slider. Perhaps you found one in the wild and your curiosity got the best of you, or maybe you have one as a pet but aren’t sure how old it is. In today’s article, I’ll walk you through several different techniques you can use to estimate the age of a red-eared slider with confidence.
How to tell age of a red-eared slider
The most reliable way to tell the age of a red-eared slider is by measuring the length of their shell.
Once you measure their shell length, you can use my size chart below to determine their approximate age.
Red-eared slider age chart
This chart shows the average shell size for a red-eared slider by age.
One important thing to keep in mind is that the size of a red-eared slider varies between males and females. As you can see above, female red-eared sliders are usually a little bigger than their male counterparts. Therefore, if you are using this method, you should make sure to know the gender of your turtle.
Once you confirm the gender of your turtle, using this chart is pretty simple. If your turtle’s shell is 1.5 inches or less, they are likely less than 6 months old. Since most pet shops sell turtles when they are 4-5 inches to reduce salmonella, most red-eared sliders sold at pet stores are usually 3-5 years old.
Red-eared sliders usually reach fully physical maturity around the age of 8. At this point, male red-eared sliders are usually between 7-9 inches, and females are around 9-12 inches.
Just like any species on the planet, there can be anomalies in a red-eared slider’s growth. They may be a couple inches small or bigger than average. A turtle’s growth can be affected by amount of food they eat, their environment, and even the size of their tank. Therefore, it’s important to keep in mind that the red-eared slider age chart is a helpful guide, but not 100% accurate for all turtles.
Another way you can estimate the age of a red-eared slider is by the scute ring method.
Counting the rings on the scutes
You may already be aware that turtles shed. While they shed to accommodate growth, the evidence of prior shedding can actually help you determine the age of a red-eared slider. It works similar to counting the rings of a tree to determine a tree’s age.
A red-eared slider typically sheds once or twice per year for the first 8-10 years of their life. Every time a red-eared slider sheds a layer of their scutes, the older layer leaves a small line at the end of the scute. Therefore, if a red eared slider is 5 years old, they would likely have 5-10 lines on the bottom of their scutes as a result of prior shedding.
Now it’s your turn! If you have a red-eared slider with 8 lines on the underside of their scutes, how old do you think they might be?
The answer: According to the scutes method, this turtle would likely be between the ages of 4 and 8!
Unfortunately this method isn’t as reliable after the ages of 8-10, because red-eared sliders shed their shells a lot more irregularly after this age.
While this method won’t give you an exact year, it is a great supplement to the size chart method. Now I will review a couple other ways you can estimate a red-eared slider’s age based on their shell.
Shell color
When a red-eared slider is born, they usually have a bright green shell. Over time, that shell transforms to a light brown, and then finally to a dark brown (or sometimes almost black) color. That means that the lighter a red-eared slider’s shell is, the younger they are. While this won’t give you an exact age, it can be a good method to compare two turtles to see which one is older.
You can learn more about shell color in my article on why is my turtle losing color.
Condition of shell
Another method that can help you estimate the age of a turtle is by assessing the condition of their shell. Turtles (especially those in the wild) tend to get more scratches and scrapes on their shell as they get older. This is natural, as older turtles have more life experience and will typically have more instances where they bump up against rocks or other hard objects.
Similar to the color method, this won’t tell you the exact age of a turtle, but you it is a great way to compare two turtles to see which one is probably older.
Take your turtle to the vet
The most accurate way to determine the age of a turtle is to get an estimate from a qualified veterinarian. They are able to guess the age of a red-eared slider by analyzing their bone structure and density. However, even vets are not 100% accurate at determining the age of a turtle, and they will likely give you a range within 1-2 years instead of an exact age.
Veterinarians usually don’t estimate a turtle’s age, since it’s rarely necessary. If your vet needs to administer a drug to your turtle, they will use their size and weight to determine dosage amount instead of age.
Why it’s important to know the age of your red-eared slider
While you will never need to know the exact age of your red-eared slider, it is helpful to know what stage of life they are in. This will help you determine how much and how often to feed your red-eared slider. It will also help you choose what type of tank you need, since that will be very dependent on how much more they have to grow.
