Box turtles often live for decades in the wild but often much less in captivity, and much of this is due to your box turtle’s aquarium size.

A big reason why is the quality of their captive environment as well as, you guessed it, the size of their tank.

What Exactly Is The Best Turtle Aquarium Size?

That will depend upon whether you have or are thinking of building an indoor or outdoor enclosure. For a big chunk of the turtle hobbyist population, the minimum size of an indoor enclosure should be 3 feet long with a width of at least 1 foot. For outdoor enclosures, a length and width of both 4 feet is standard minimum practice.

Now, I wish that was all there was to it, in which case I could cut this post way short, but there’s a bit more, so bear with me.

For starters, here is my favorite aquarium for box turtles: Box Turtle Tank

Do Box Turtles Need To Be Outside?

Do you want an indoor or outdoor enclosure for your box turtle?

This might be one of the more difficult choices you’ll have to make, but it’s also one of, if not the, most important.

Ignoring all other factors, an outdoor enclosure is superior to an indoor habitat for nearly any given box turtle, because:

• It will have a much larger space to live in.
• It will likely have an abundant supply of natural sunlight.
• An outdoor enclosure mimics the natural environment a box turtle lives in, to a much larger degree.

If only it were that easy! On the other hand, there are several disadvantages to establishing an outdoor habitat, namely that:

• You will have much less control over the temperature, and in turn, your turtle’s health.
• Depending upon where you live, it may simply be too cold for your box turtle during the winter months.
• Your turtle will likely be at increased risk of harm from predators.

Here is my personal recommendation.

1. If you have enough space around your home.
2. And if you own a box turtle which is either native to the region you live in, or fairly close, an outdoor enclosure is probably going to be a better choice.

If you cannot tick off both of those boxes, go the indoor route.

By far, the biggest advantage of an indoor enclosure for a box turtle is your ability to have more control over the temperature and humidity.

What Is The Ideal Box Turtle Aquarium Size?

Here’s the thing about the size of your box turtle tank (or aquarium or enclosure).

The “ideal” size is the biggest one you can provide.

When it comes to tank sizes, bigger is almost always better. The reason for this is simple. In their native habitat, turtles (whether box or aquatic), aren’t limited to an enclosure that is a few feet long and wide.

That being said, there are minimum size guidelines that are accepted by the pet turtle community in general. Those being:

• With outdoor enclosures, go for a minimum size of 4 feet long and wide.
• As for indoor habitats, don’t go smaller than 3 feet in length and 12 inches in width.
• For indoor enclosures, add another foot in length and a half a foot in width for every extra turtle inside.

If you opt for an indoor enclosure, try your best to make it look as if your box turtle were living outside. This will go a long way with respect to reducing environmental stress.

Whatever you do, don’t ever use a glass tank to house your box turtle. Or at the very least, don’t use a plain glass tank without a bit of customization.

Why?

Your box turtle does not understand glass. It sees right through it, tries to move through it, yet can’t. This is quite stressful for your animal and will lead to:

• Your box turtle trying to endlessly climb out.
• The turtle suffering from undue anxiety, which may shorten its lifespan.

What Do You Need For A Box Turtle Habitat?

There’s another reason why bigger is almost always better when it comes to box turtle habitats; you’re going to need to put a lot of things inside it!

Substrate

Perhaps the most important thing regarding what goes inside your habitat is the substrate you choose.

In fact, according to a study done in Applied Animal Behavior Science, eastern box turtles that were housed in enriched-environments (Cyprus mulch substrate and a hide) showed better overall blood health and tried to escape far less those housed in barren environments with just newspaper.

Substrate is the type of substance that your box turtle will live on. Some common types of substrate include:

• Soil
• Coconut fiber, husk or shell
• Sphagnum moss
• Cypress mulch
• Leaf litter

Different substrates work best with different species of box turtle, but a good rule of thumb is to pack your substrate at least 3 inches deep. This is because box turtles need to burrow in order to feel safe and secure.

This is also an important reason why bigger enclosures or tanks are better; you’ll need quite a bit of substrate. For outdoor enclosures, there is another important caveat, you’ll need to provide a barrier that extends at least 6 inches underneath your habitat’s walls in order to prevent your box turtle from escaping.

For substrate recommendations, click here.

Water Dish

You’ll also need some type of large water dish, which again, will fit much better into a bigger aquarium or tank.

Your water source needs to be shallow enough to soak at least the bottom half of your turtle’s body and also allow it to eat (turtles lack saliva and need water to help swallow and process food). I have found that plant saucers work pretty well serving this purpose.

This will also probably need to be cleaned daily, as box turtles are quite dirty, messy creatures. Chlorine-free water is strongly recommended.

Unfortunately, we’re not done just yet! So far, I’ve said that your enclosure will need to be big enough to accommodate:

• 3-inch deep substrate.
• A large, shallow water dish or bowl.

Hiding Spots

You’re also going to need hiding places!

As I noted above, box turtles love to burrow to feel safe. Ditto for an above-ground hiding place. This will also make your enclosure feel more natural.

The best hiding places for box turtles in my opinion are:

• Hollowed out logs.
• Plants (real or fake).
• Large stones or rocks (these also serve the purpose of helping to keep your box turtle’s claws filed down).

Bonus points if you’ve got an enclosure big enough to accommodate all 3!

So far I’ve said that:

1. The bigger your box turtle aquarium size, the better.
2. You’ll need to put substrate at least 3 inches deep inside.
3. You’ll also need to make your turtle’s enclosure more natural by adding a shallow water dish, as well as hiding places.

There’s one more reason why bigger is better when it comes to your enclosure.

Temperature Gradients For Box Turtles

Because box turtles are unable to regulate their own body temperature, they need to use the sun to warm up, and shaded areas or water to cool down.

To help create this for your turtle, your enclosure will need something called a temperature gradient.

A temperature gradient simply means that one end of your enclosure is cool, the other is hot and in between it slowly gets hotter and cooler.

And if you’ve got a small enclosure, this is almost impossible to pull off correctly, which is yet another reason why bigger is better.

The easiest way to set up a temperature gradient is to simply place your UV-light at one end of your enclosure, and check that it’s around 80 to 85 degrees Fahrenheit. Putting your light on a flat rock works really well as a basking spot.

Ideally, your cool end will be somewhere in the high 60’s to anywhere in the 70s. Your water dish should go over here.

At night, if the temperature drops into the low 50s on the cool side you’ll probably need to get a heat lamp in order to stave off illness.

Don’t make the same mistake I did in thinking that because your turtle is able to survive the winter outside, it won’t need a heat lamp. Lots of wild turtles don’t make it through the winter.

Box Turtle Temperature Guidelines

For the most common species of box turtle, which tend to be:

• Florida and Gulf Coast box turtles
• 3-toed box turtles
• Eastern box turtles
• Spotted and Desert box turtles

Some general temperature guidelines are:

• High 60s to anywhere in the 70s on the cool end.
• Low to mid 80s in the basking spot.
• Not too far below 60 degrees at night.

Most of these species thrive in higher humidity levels, which you can achieve by using a good substrate that holds in moisture (like soil or sphagnum moss) as well as daily misting.

Summary

The cliff’s notes version of this article is as follows:

• The best box turtle aquarium size is to get the biggest enclosure you can.
• For an outdoor enclosure, the minimum size is 4 feet in length by 4 feet in width.
• For an indoor habitat, the minimum size should be 3 feet in length by 1 foot in width.
• Substrate should be at least 3 inches deep.
• A shallow water dish and hiding places are a must.
• A bigger enclosure allows you to more easily maintain a temperature gradient.