5 gallon tank: size, liters and setup numbers
A 5 gallon tank is the smallest size most keepers recommend for a single betta or a small shrimp colony. Small volumes swing in temperature and water quality quickly, so steady heating and regular small water changes matter more here than in bigger tanks.
| Typical dimensions | 16 × 8 × 10 in 40.6 × 20.3 × 25.4 cm |
|---|---|
| Volume | 5 US gallons 18.9 liters |
| Realistic water after substrate and decor | About 4.2 gal About 16.1 L |
| Water weight | About 42 lb About 19 kg |
| Gravel for a 1 inch bed | About 7 lb About 3 kg |
| Gravel for a 2 inch bed | About 15 lb About 7 kg |
| Heater (room 8°F / 4.4°C cooler) | 25 W |
| Heater (room 15°F / 8.3°C cooler) | 50 W |
| Filter flow (4 to 6 times per hour) | 20 to 30 GPH 76 to 114 L/h |
Dimensions vary a little between brands. For exact numbers, measure your tank and use the calculators below.
Plan the rest of your 5 gallon tank
Common questions
- How many liters is a 5 gallon tank?
- A 5 gallon tank holds about 18.9 liters when filled to the brim. With substrate and decorations, the real water volume is usually closer to 16 liters.
- How much does a 5 gallon tank weigh when full?
- The water alone weighs about 42 pounds (19 kg). Glass, substrate and rock add more on top, so choose a stand rated for the full weight.
- What size heater does a 5 gallon tank need?
- If your room stays around 8°F below your target water temperature, a 25 W heater is a good fit. For colder rooms, around 15°F below target, go with 50 W.