How to calculate water tank capacity in kL
Capacity is the tank's inside volume. Because 1 cubic metre equals 1 kilolitre, measure the tank in metres and the volume in cubic metres is already the capacity in kL. Use inside measurements and, for a tank that is not full to the brim, the working height up to the overflow level.
Rectangular tank example
2 m × 1.5 m × 1.2 m = 3.6 m³ = 3.6 kL (3,600 litres).
Cylindrical tank example
Diameter 2 m, height 3 m: π × 1² × 3 = 9.42 m³ = 9.42 kL.
How is kL per cm calculated in storage tanks?
Storage tanks are often measured with a dip stick in centimetres, and the reading is converted to kL. For a tank with a constant cross-section, each centimetre of height holds the same amount: the base area in square metres multiplied by 0.01 m gives cubic metres, which equals kL. A 3 m² base holds 0.03 kL (30 L) per cm. Spheres, sloped bottoms and other irregular tanks do not have a constant value, so use the maker's calibration chart for them.
Measuring tips
- Measure the inside, not the outside, of the tank.
- Deduct for fittings or partitions that take up space.
- For a partly filled tank, enter the water level to see the volume currently stored.