What is the formula for cylinder volume?

The volume of a cylinder is V = pi times r squared times h, where r is the radius of the circular base and h is the height (or length, if the cylinder is lying on its side). If you only know the diameter, divide it by two to get the radius before applying the formula. The result is in cubic units matching whatever unit you measured radius and height in, for example cubic metres if you measured in metres.

How do you convert cylinder volume to litres or gallons?

One litre equals 1,000 cubic centimetres, or 0.001 cubic metres. So a volume in cubic metres multiplied by 1,000 gives litres. To convert litres to US gallons, divide by 3.785411784. To convert litres to imperial (UK) gallons, divide by 4.54609. These are the standard conversion factors used worldwide, including in New Zealand, which uses litres as its everyday liquid volume unit.

Does it matter if the cylinder is standing up or lying on its side?

No, total volume is the same either way because volume only depends on the radius of the circular cross-section and the overall length along the cylinder's axis. Orientation only matters if you need the volume of liquid at a partial fill level, which requires a different, more complex partial-volume formula for a horizontal cylinder.

Cylinder Volume Calculator

Work out the volume of a cylinder using its radius or diameter and its height (or length). Get instant results in litres, cubic metres, cubic centimetres, US gallons, and imperial gallons. Useful for water tanks, drums, pipes, and cylindrical containers.

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Method note Standard geometric formula V = πr²h with fixed international unit conversion factors.

1. Dimensions

Measure by

Radius

Diameter

Height / length

Unit of measurement

2. About This Calculator

This calculator uses the standard cylinder volume formula: volume equals pi multiplied by the radius squared, multiplied by the height. All results update live as you change the dimensions above.

Results are shown in litres, cubic metres, cubic centimetres, US gallons, and imperial (UK) gallons, so you can use whichever unit suits your tank, drum, or pipe.

Cylinder Volume

Litres
-
L

Cubic Metres

m³

US Gallons

gal (US, liquid)

Imperial Gallons

gal (UK)

Calculation Breakdown

Radius used-

Height / length used-

Radius squared-

Volume (radius² × height)-

Volume × π-

All Unit Results

Cubic centimetres (cm³)-

Cubic metres (m³)-

Litres (L)-

US gallons-

Imperial (UK) gallons-

How Cylinder Volume Is Calculated

A cylinder is a solid with two parallel circular ends connected by a curved side. Its volume is the area of one circular end multiplied by the height (or length) between the two ends. The formula is:

V = π × r² × h

Where r is the radius of the circular cross-section and h is the height or length of the cylinder. If you have the diameter instead of the radius, divide the diameter by two before squaring it. Pi (π) is approximately 3.14159265.

Converting Volume to Litres and Gallons

Conversion	Factor
1 cubic metre (m³) to litres	1,000 L
1 litre to cubic centimetres	1,000 cm³
1 litre to US gallons	÷ 3.785411784
1 litre to imperial (UK) gallons	÷ 4.54609
1 US gallon	3.785411784 L
1 imperial gallon	4.54609 L

New Zealand uses litres and cubic metres as standard measurements for tanks, drums, and containers, but US and imperial gallons are shown here too since many imported tanks, pumps, and pipe specifications are still labelled in gallons.

Common Uses for This Calculator

Sizing a water tank or rainwater collection cylinder
Working out how much liquid a drum or barrel holds
Estimating the internal volume of a section of pipe
Checking the capacity of a cylindrical planter, silo, or storage container
Converting an imported tank's gallon rating into litres for New Zealand use

Worked Example

A cylinder with a radius of 0.5 m and a height of 1 m has a volume of π × 0.5² × 1 = π × 0.25 = 0.7854 m³. Converting to litres: 0.7854 × 1,000 = 785.4 L. In US gallons that is 785.4 ÷ 3.785411784 = 207.5 gallons, and in imperial gallons it is 785.4 ÷ 4.54609 = 172.8 gallons.

Related Calculators

Sources: Standard geometric formula for cylinder volume (V = πr²h). NIST Handbook 44, Appendix C: General Tables of Units of Measurement (US gallon and imperial gallon conversion factors).

This calculator provides a geometric estimate of internal volume based on the dimensions you enter. It does not account for wall thickness, tapered ends, internal fittings, or partial-fill levels in a horizontal cylinder. For tank purchasing or engineering decisions, confirm the manufacturer's stated capacity.

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