If you have pet turtles, there’s a pretty good chance you’ve wondered yourself “how fast do pet turtles grow?”

Turtle Growth Rate Factors

The answer, it depends. Here’s why:

  • what kind of turtle is it? Different species grow to different sizes. Some top out at 4″ SCL (straight carapace lenght), others at 12″, others 24″, 36″ or even bigger or smaller.
  • How often are they fed? Naturally, turtles that are fed more often will grow faster.
  • What are they fed? More protein/calcium content in the diet leads to more growth
  • How active are they, what’s their metabolism like? Turtles have their own unique characteristics and personalities. Some turtles, even when comparing within the same species, will be more active than others. Their level of activity is an indicator for where their calories go, towards burned energy or growth.
  • How healthy are they? Obviously a sick turtle will not grow at the same rate as a healthy turtle. Remember that a properly set-up habitat is the first step to take in helping a sick turtle.

While some of these reasons are a bit obvious, wouldn’t you still like to know how fast pet turtles grow? Surely there must be a rough estimation for what an average pet turtle will grow within average/normal circumstances. As a general rule of thumb, turtles will grow the most in their first year of life, then the growth rate slows thereafter. But what does that means exactly?

So let’s look at my pet turtles….

What About my turtles

My pet turtles are red ear slider turtles, Rex and Cinderella. Rex is a male, Cinderella a female. Male RES (red eared sliders) typically max out at a size of 8″ SCL, while females usually grow to 12″ SCL.

I fed them Zoo Med Hatchling Aquatic Turtle Food until they grew to 2″ SCL at the manufacturer recommended rate of twice a day (I think it was). This food is composed of 43% protein. I then gave them Zoo Med Growth Formula for a while and changed their rate to the realistic feeding rate of every other day. This food is 35% protein. At some point I switched them to the Maintenance Formula (25% protein) and fed then twice a week.

Their level of activity was almost the same, although Rex was the more active of the two.

How fast did my pet turtles grow

I overfed them when they were younger (following food manufacturer feeding guidelines) and corrected their feeding when I learned more about how to feed them properly. Although Rex was a bit more active, he grew much faster and also developed more shell pyramiding then Cinderella. After correcting their feeding pattern, Rex’s growth rate slowed until he reached his max and Cinderalla more or less kept her growth rate.

With that said, here’s a dandy little chart of their size and growth rate:
note: Week 1 is when I first measured them, not their hatch size. Measurements are in SCL inches.

  Week    Rex    Cinderella  
  1  1.5  1.3
  3  1.6  1.4
  4  1.8  1.5
  5  1.9  1.5
  8  2.1  1.9
  11  2.3  2.1
  14  2.3  2.1
  16  2.4  2.3
  23  2.7  2.5
  104  5.9  5.9

Visually, here is how fast both my turtles grew, with a handy trend-line to boot. Blue is Rex (male), Red is Cinderalla (female):

my red ear slider turtles growth over time
Note: I stopped measuring them altogether after the 104’th week

How fast did others’ pet turtles grow

Answers on the web were not very clear as to how fast (or slow) turtles grow. Most times the question is asked on a forum or question and answer website (like this), the typical response is along the lines of “be prepared to have your turtle grow to its max size, get the biggest tank you can get”.

Every now and than, you get something more concrete like “they grow to 4” inches in the first year, such as from wiki answers. Some say that it can take 7-8 years for a slider to reach full growth (turtleforum.com), but again, there are so many factors.

Pet turtles grow this much

Here’s a photo of an 11″ SCL female red ear slider.

Note: when measuring the Straight Carapace Length of a turtle, just measure the length of the shell only.

Female red ear sliders will grow up to 12″ and males to 8″. Other species have different max sizes. Some musk turtles and other endangered turtles have max sizes of 4″. It is illegal to keep an endangered turtle as a pet. Needless to say, your pet turtle will grow big.

In closing

When getting a turtle as a pet, please keep in mind that they will grow, regardless whether it takes them 7 years or 20. They will need a habitat that is the proper size for them (not small), so please keep that in mind when setting up their habitat.

So, how about your pet turtles. How fast did they grow?

*photo by Dan Machold, cropped | Some rights reserved


  1. I have 21 red eared sliders from about the size of 1.5inch, because i live in a warmer environment they are very active. I fed them since young twice a day, as well as koi in the pond, they regularly finish their food, fresh vegtables and nibbling on the kois food. So realistically they being overfed.

    All turtles grew similar to what your graph shows, i expect full max at 3.5 years.

  2. The picture you have posted of the female slider is measured in cm, not inches (so just over 4 inches) But otherwise great article! I would love to see more people posting growth rates. I’ve had a male RES over 7 years and he never did grow past 4 inches even with a proper setup. With nearly identical conditions I have a hatchling that has grown an inch in three months.. One never knows what to expect!

    1. hmmm, had not noticed that!! It’s a picture from flickr….

      That is quite a big difference you’ve experienced.