How do you calculate water tank volume?

Calculating the volume of a water tank depends on its shape. Here's how to calculate the volume for common tank shapes:

1. Rectangular or Cuboid Water Tank

This is the simplest calculation. You need the length (L), breadth (B), and height (H) of the tank.

Formula: Volume = L x B x H
Example: Let's say your tank is 8 ft long, 6 ft wide, and 5 ft high.
Volume = 8 ft x 6 ft x 5 ft = 240 cubic feet (ft³)
Conversion to Liters: Since 1 ft³ is approximately 28.31 liters, the tank's volume in liters is: 240 ft³ x 28.31 liters/ft³ = 6794.4 liters

For a cylindrical tank, you need the radius (r) of the circular base and the height (h) of the cylinder.

Formula: Volume = πr²h (where π ≈ 3.14159)
Example: If the tank has a radius of 2 ft and a height of 5 ft:
Volume = 3.14159 x (2 ft)² x 5 ft = 62.83 ft³
Volume in Liters: 62.83 ft³ x 28.31 liters/ft³ = 1778.12 liters

For a spherical tank, you only need the radius (r) of the sphere.

Formula: Volume = (4/3)πr³
Example: If the tank has a radius of 3 ft:
Volume = (4/3) x 3.14159 x (3 ft)³ = 113.1 ft³
Volume in Liters: 113.1 ft³ x 28.31 liters/ft³ = 3202.86 liters

If your water tank has an irregular shape, the volume calculation can become more complex. In these cases, consider the following:

Decomposition: Try to break down the irregular shape into simpler, known shapes (e.g., a cylinder with a conical bottom). Calculate the volume of each part and add them together.
Integration (Calculus): If you have a mathematical description of the shape, you can use integration to find the volume.
Liquid Displacement: You can fill the tank with a known volume of water (e.g., using calibrated containers) and measure how much liquid it takes to fill the tank completely. This provides the volume directly.

Tank Shape	Formula	Example (ft)	Volume (ft³)	Volume (Liters)
Rectangular	L x B x H	8 x 6 x 5	240	6794.4
Cylindrical	πr²h	r=2, h=5	62.83	1778.12
Spherical	(4/3)πr³	r=3	113.1	3202.86