About the Volume Calculator
Volume Calculator finds the volume and surface area of seven common solids: cube, box, cylinder, sphere, hemisphere, cone and pyramid with a rectangular base. Choose the shape and a unit from millimetres to yards, type the measurements shown on the sketch, and the result appears together with a capacity table in litres, millilitres, US gallons, cubic metres and cubic feet. The formulas describe ideal solids measured on the inside of the walls, so the usable volume of a real tank is a little smaller because of fittings, slopes and the fill level. Gallons are US gallons, not imperial ones. The surface area of a cone, a hemisphere and a pyramid includes the base.
Updated October 2026
How to use the Volume Calculator
- 1Choose the shape and the unit you measured in.
- 2Type each measurement using the labelled sketch.
- 3Read the volume and the surface area.
- 4Look at the capacity table for litres, US gallons and cubic feet.
- 5Copy the result, or press Reset for a new shape.
Volume formulas for common solids
- Cube: side × side × side. Box: length × width × height.
- Cylinder: π × radius² × height.
- Sphere: 4/3 × π × radius³. Hemisphere: half of that.
- Cone: 1/3 × π × radius² × height.
- Pyramid: 1/3 × base length × base width × height.
From cubic units to litres and gallons
A cube 10 centimetres on each side has a volume of 1,000 cubic centimetres and holds exactly one litre. One cubic metre is 1,000 litres. The tool converts your volume to cubic metres first and then to litres, millilitres, US gallons and cubic feet, so you do not need to convert the measurements beforehand.
US gallons are about 3.785 litres. If you buy in imperial gallons, divide the litres by 4.546 instead.
Tanks, pools and containers
For a rectangular pool or tank use the box shape with the water depth as the height. A round tank is a cylinder. Measure inside the walls, because the thickness of the material would otherwise add to the size, and subtract any fittings that take up space.
The geometric volume is the most the container could hold. Real tanks are seldom filled to the brim, and the outlet, the slope of the floor and the air gap at the top reduce what you can use.
Measuring tips
Use one unit for all measurements. Measure the radius, not the diameter, or halve the diameter first. For cones and pyramids, the height is straight up from the base to the tip, not along the sloping side.
To compare a floor plan with the volume of the room, work out the floor first in Area Calculator, and to change units of length or capacity use Unit Converter. For mixed amounts use the Fraction Calculator, and the Online Calculator handles quick sums.
Features
- Seven solids from cube to pyramid
- Volume and surface area
- Units mm, cm, m, in, ft and yd
- Capacity in litres, millilitres, US gallons and cubic feet
- Labelled sketch of each shape
- Clear messages for missing measurements
- Runs in your browser
Frequently asked questions
How do I calculate the volume of a box?
Multiply length by width by height. A box 2 by 3 by 4 units holds 24 cubic units. Choose Box, enter the three measurements in the same unit, and the tool also gives the surface area and the capacity in litres.
How many litres are in a cylinder?
Work out the volume, π × radius² × height, in cubic centimetres and divide by 1,000. A cylinder with a radius of 10 cm and a height of 30 cm has a volume of about 9,425 cubic centimetres, which is about 9.4 litres. Choose the unit cm and read the litres row.
What is the volume of a sphere formula?
It is four thirds times π times the radius cubed. A sphere with a radius of 3 has a volume of about 113.1 cubic units. The surface area is 4πr², which happens to be the same number for a radius of 3.
How do I convert cubic feet to litres?
Multiply cubic feet by 28.3168. To do it here, choose the unit ft, enter the measurements of a shape that has the volume you want, and read the litres row. One cubic foot is about 28.3 litres and 7.48 US gallons.
What is the difference between volume and capacity?
Volume is the space a solid takes up, in cubic units. Capacity is how much a container can hold, usually in litres or gallons. For an empty container measured inside, the two are the same amount in different units, and 1,000 cubic centimetres is one litre.
How do I find the volume of a half-full tank?
For a box-shaped tank, use the depth of the liquid as the height. For a cylinder standing upright, do the same. A cylinder lying on its side needs a different formula that this calculator does not cover, so treat those results with care.