Tank Volume Calculator Litres Formula

This calculator works out the volume of a rectangular, cylindrical, or spherical tank in litres. You enter the tank’s dimensions (length, width, height, or diameter), and it returns the volume in litres, along with the volume in cubic metres and US gallons. The formulas used are the standard geometric volume equations converted to litres.

Formula

The volume of a tank is calculated using the standard geometric formulas for each shape, then converted to litres (1 cubic metre = 1000 litres).

• Rectangular tank: Volume (litres) = length (m) × width (m) × height (m) × 1000
• Cylindrical tank: Volume (litres) = π × (diameter/2)² × height (m) × 1000
• Spherical tank: Volume (litres) = (4/3) × π × (diameter/2)³ × 1000

Variables:

• length, width, height – in metres (m)
• diameter – in metres (m)
• π ≈ 3.14159
• 1000 – conversion factor from cubic metres to litres

Worked Example

Using the default values from the calculator: a rectangular tank with length = 1.2 m, width = 0.6 m, height = 0.8 m.

1. Calculate the volume in cubic metres: 1.2 × 0.6 × 0.8 = 0.576 m³
2. Convert to litres: 0.576 × 1000 = 576 litres

The calculator shows 576.00 litres, which matches the worked example.

When to Use This Calculator

Use this calculator when you need to know the capacity of a tank for water storage, aquaculture, fuel, chemical storage, or any other liquid. It is also useful for planning aquarium sizes, rainwater collection, or determining how much liquid a custom tank can hold. The calculator assumes the tank is completely filled and has straight, uniform sides (for rectangular and cylindrical tanks). For partially filled tanks, you would need to adjust the height or use a more complex formula.

How to Read the Result

The main result is the volume in litres, which is the standard unit for liquid capacity in most of the world. The calculator also shows the volume in cubic metres (useful for construction or shipping) and US gallons (common in the United States). If you need imperial gallons, multiply the litres by 0.219969.

Common Mistakes and Unit Mix-Ups

• Mixing units: The formulas require all dimensions in metres. If you measure in centimetres, divide by 100 first. If in inches, multiply by 0.0254.
• Forgetting the conversion factor: The formulas give cubic metres, not litres. Multiply by 1000 to get litres.
• Using diameter instead of radius: For cylindrical and spherical tanks, the formula uses radius (diameter/2). Using diameter directly will give a volume four times too large.
• Rounding too early: Round only the final answer, not intermediate steps, to avoid errors.

Limitations of the Formula

These formulas assume perfect geometric shapes. Real tanks often have rounded corners, dished ends, or tapered sides, which will make the actual volume slightly different. For irregular shapes, consider using a water displacement method or a more advanced volume calculation. Also, the calculator gives the total volume, not the usable volume – you may need to leave some space for expansion or air, especially for liquids that expand with temperature.

Alternative Methods

If you don’t have the dimensions, you can measure the volume by filling the tank with a known quantity of liquid (e.g., using a flow meter or a bucket of known volume). For existing tanks, you can also calculate volume by measuring the time it takes to fill at a known flow rate. For complex shapes, you can break the tank into simpler geometric parts and sum their volumes.

Frequently Asked Questions

How do I convert from cubic feet to litres?

One cubic foot equals 28.3168 litres. So multiply the volume in cubic feet by 28.3168 to get litres. For example, a 10 cubic foot tank is 283.168 litres.

What is the formula for a rectangular tank in inches?

If you measure in inches, first convert to feet (divide by 12) or to metres (multiply by 0.0254). Then use the formula: length × width × height (in metres) × 1000. Alternatively, use length (in) × width (in) × height (in) / 61.0237 to get litres directly.

Does the formula work for any liquid?

Yes, the volume calculation is independent of the liquid. However, the weight will vary with density. For water, 1 litre weighs about 1 kilogram. For other liquids, multiply the volume by the density (kg/L) to get the mass.

How do I calculate the volume of a horizontal cylindrical tank?

For a horizontal cylinder, the formula is more complex because the filled volume depends on the liquid depth. The total volume is still π × r² × length, but the partial volume requires a segment area formula. This calculator assumes a vertical cylinder (full height).

What is the difference between US gallons and imperial gallons?

US gallons are smaller. 1 US gallon = 3.78541 litres, while 1 imperial gallon = 4.54609 litres. The calculator shows US gallons by default.

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in shape | Tank shape | Rectangular=1, Cylindrical=2, Spherical=3 | 1 | 0
in len | Length (for rectangular) | m | 1.2 | 0
in wid | Width (for rectangular) | m | 0.6 | 0
in hei | Height / Length (for cylindrical) | m | 0.8 | 0
in dia | Diameter (for cylindrical or spherical) | m | 0.5 | 0
out vol | Volume | litres | shape * len * wid * hei + (shape==2 ? pi * (dia/2)^2 * hei * 1000 : 0) + (shape==3 ? (4/3) * pi * (dia/2)^3 * 1000 : 0) | 2
out m3 | Volume | cubic metres | vol / 1000 | 3
out gal | Volume | US gallons | vol * 0.264172 | 2