What size tank does a turtle need?
With our turtle tank size calculator, you can identify what size tank your turtle needs to grow, thrive, and live its best life. Just insert your turtle's current size, and our calculator will take care of the rest.
If you've read anything about turtles, it's hard not to be impressed by them 🐢. Compared to dogs, cats, rats, and other furry pets, they simply eat, swim, bask, and stay in their tanks all day, but they can live to be 100 years old!
If you're a new turtle parent, you might think that getting a tank with a bit of water and rocks would be enough. Yes, they generally like to keep things simple. However, it's important to provide them with the right necessities in order for them to be comfortable. A turtle's tank is not just where they live but their entire existence!
Like any living creature, turtles deserve to feel safe and happy in their homes. In their natural habitats, they spend a lot of time in the water and basking in the sun. When kept as a pet, turtles will need the optimum tank size for swimming and a land area for sunning to be happy and healthy.
So now you're probably wondering how big should your turtle tank be. Generally, it's recommended to start with at least a 50-gallon tank even if your pet turtle is smaller than 5 inches (12 cm) since they will usually grow to that size anyway.
More importantly, the tank size depends on the species of your turtle. Turtle sizes differ from species to species. Most turtle species that are kept as pets could grow up to 12 inches (30 cm). For example, the common musk turtle, one of the most popular aquatic turtle species because of how small they are, only grow up to 5 inches (12 cm) and a musk turtle tank size should be 50 gallons or more.
However, while some species will remain relatively the same size, others can grow over two feet long. For instance, the biggest tortoise you can keep as a pet is the Sulcata, which grows up to 30 inches (76 cm) with an average weight of 100 pounds (45 kg)!
How to use the turtle tank size calculator?
Our turtle tank size calculator is simple. We follow the general rule that a turtle needs at least ten gallons of tank volume for every inch of shell length. While this is a good approximation, a larger tank size will always be the more suitable option for your pet turtle. In this case, bigger is always better.
Tank size (gallons) = Turtle Size (in) × 10 gallons
- Select your measurement system — American (inches/gallons) or Metric (cm/liters).
- Enter your turtle's Straight Carapace Length (SCL) — measure from the front to the back of the shell in a straight line.
- Optionally enter the tank cost and select your currency (USD, RUB, EUR, and more) to estimate expenses.
- Click Calculate to see the minimum and recommended tank sizes.
The calculator shows you both the minimum tank size (10 gallons per inch) and a recommended size (15 gallons per inch) — because a more spacious environment is always better for your turtle's wellbeing.
How large can my turtle grow?
Turtle size depends greatly on species. Here are some common pet turtle species and their typical adult sizes:
| Species | Adult Size | Min. Tank |
|---|---|---|
| Musk Turtle | 4–5 in (10–12 cm) | 40–50 gal (150–190 L) |
| Painted Turtle | 5–10 in (12–25 cm) | 50–100 gal (190–380 L) |
| Red-Eared Slider | 6–12 in (15–30 cm) | 60–120 gal (225–450 L) |
| Map Turtle | 6–10 in (15–25 cm) | 60–100 gal (225–380 L) |
| Box Turtle | 5–7 in (12–18 cm) | 50–70 gal (190–265 L) |
| Sulcata Tortoise | 24–30 in (60–76 cm) | 240+ gal (900+ L) or outdoor enclosure |
How to set up a turtle tank
Once you know the right tank size, setting it up correctly is crucial for your turtle's health. Here are the key elements:
- 🌊 Water area: At least 75% of the tank should be water, deep enough for your turtle to swim and flip over if it turns upside down.
- ☀️ Basking area: A dry land area where your turtle can fully dry off and warm under a UVB lamp. This is essential for shell health.
- 💡 UVB lighting: Turtles need UVB rays for vitamin D3 synthesis and calcium absorption. Without it, they can develop metabolic bone disease.
- 🌡️ Temperature: Water temperature should be 75–80°F (24–27°C). Basking spot should be 85–95°F (29–35°C).
- 🔄 Filtration: A powerful filter rated for at least twice the tank volume is essential. Turtles produce a lot of waste.
- 🪨 Substrate: Large smooth river rocks or bare bottom are safest. Avoid small gravel that turtles can accidentally swallow.
Fact or Fiction: Turtles don't grow any bigger than their tank
Fiction! This is one of the most dangerous myths about turtle care. Turtles will continue to grow regardless of tank size — but in a small tank, they grow in an unhealthy, stunted way. A cramped environment leads to:
- Stunted and deformed shell growth (pyramiding)
- Increased stress and aggression
- Poor immune function and susceptibility to disease
- Shortened lifespan
Always provide the right-sized tank for your turtle's species and current size, with room to grow. Remember: turtles can live 20–100 years depending on the species, so investing in proper housing pays off for decades.