Tank Volume Calculator
Choose the tank shape and enter its measurements.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Cylinder: volume = π × (diameter ÷ 2)² × height (or length)
- Box: volume = length × width × height
- Litres = m³ × 1,000
For a swimming pool, use the pool volume calculator.
Worked example
A vertical tank 1 m across and 2 m high:
- 1.571 m³, about 1,571 litres
- The full tank of water weighs about 1.57 tonnes
Why your number may differ
Use inside measurements, not the outside size. Domed or cone-shaped tops and bottoms change the capacity a little.
Frequently asked questions
How do I calculate tank capacity?
For a cylinder, volume = π × (diameter ÷ 2)² × height or length. For a box, length × width × height. 1 m³ is 1,000 litres.
Does the full volume equal the usable water?
Usually not. Outlets and overflow pipes sit above the bottom and below the top, so usable capacity is a little less.
How much does the water weigh?
About 1 kg per litre. A 1,000 litre tank holds a tonne of water, so check the stand or roof can carry it.