Cube Volume Calculator
A cube has only one measurement, so its volume is that side multiplied by itself twice: s³. Type the side and the answer appears beside a labelled drawing of the cube, with the formula on the stage and the working, your own number put in, as the first row below: a side of 2 m gives 2³ = 8 and an answer of 8 m³. This page opens the calculator on the Cube whatever shape you used last, takes metres, centimetres, feet or inches, and lists the same volume in litres, US gallons and UK gallons plus three more cubic units underneath. Sides that are not all equal make a box rather than a cube, and Box sits on the same shape row with a length, a width and a height.
Cube · s³8,000 L · 2,113.38 US gal · 1,759.75 UK gal
One side, cubed.
The formula is on the stage, and the working is the first row. Every answer here is one textbook formula with your numbers put in, printed so you can check it: a cylinder is π r² h, a sphere is (4/3) π r³, a pool is length times width times the average of its two depths. The horizontal tank uses the exact circular-segment formula for a partial fill, so half way up is exactly half and a quarter of the way up is less than a quarter, because the bottom of a circle is narrow. Conversions use exact definitions: a litre is 1,000 cm³, a US gallon is 231 cubic inches and a UK gallon is 4.54609 litres.
Common questions
- What is the formula for the volume of a cube?
- s³: the side times itself, times itself again. The formula sits beside the drawing and the first row underneath, The working, repeats it with your number in, so a side of 2 m reads 2³ = 8 and the rows give 8,000 litres, about 2,113.38 US gallons and about 1,759.75 UK gallons. Because the side is cubed, doubling it multiplies the volume by eight: a 1 m cube holds 1 m³, or 1,000 litres, and a 2 m cube holds 8 m³.
- How many litres is a cube of a given size?
- Set the unit to cm and the litres row sits directly under the answer, because 1,000 cubic centimetres are exactly one litre. A 10 cm cube is 1,000 cm³, which is 1 litre on the nose. A 30 cm cube is 27,000 cm³, or 27 litres. A 40 cm cube aquarium is 64,000 cm³, which the rows read as 64 litres and about 16.907 US gallons. In metres the volume is already in cubic metres and each one is 1,000 litres, so a 0.5 m cube is 0.125 m³ and 125 litres.
- I know the volume and want the side. Does it work backwards?
- Not on this page: it takes a side and returns a volume, in that direction only. The side you want is the cube root of the volume, so a cube of 27 m³ has 3 m sides because 3³ = 27, and 8 m³ gives 2 m. When the volume is not a neat cube, take the cube root elsewhere and type it back in here to check the rounding: 5 m³ is a side of roughly 1.70998 m, and typing 1.70998 makes the working row read 1.70998³ = 5.00003555605.
- My sides are not all the same length. Can I still use this?
- Then the shape is a box, not a cube, and Box is the first button on the shape row: it asks for a length, a width and a height instead of one Side. The difference is worth the extra click, because cubing the wrong number compounds. A carton 2 m by 2 m by 1.9 m is 7.6 m³ as a box, while treating it as a 2 m cube claims 8 m³, an overstatement of 400 litres.
- I measured the diagonal rather than a side. What do I type?
- Convert it first. The cube takes a single side and nothing else: the Radius and Diameter switch belongs to the round shapes and never appears here. A cube's space diagonal, corner to opposite corner, is the side times the square root of 3, and a face diagonal is the side times the square root of 2. So a cube with a 10 cm space diagonal has sides of 10 / 1.7320508 = 5.7735 cm, and typing 5.7735 in centimetres gives 192.44982054 cm³, about 0.192 of a litre.
- How do I get cubic feet or cubic yards from a cube?
- Pick ft on the unit row and type the side in feet. The answer comes back in cubic feet and the rows underneath add cubic yards, cubic metres and cubic inches along with litres and both gallons. A 3 ft cube is 27 ft³, and the Cubic yards row reads exactly 1, because a cubic yard is 27 cubic feet. A 4 ft crate is 64 ft³, which the rows give as 2.37037037037 cubic yards and 1,812.27818189 litres. A 1 ft cube is 1 ft³, the same 1,728 cubic inches you get by typing 12 with the unit on in.
- Which units can I type the side in, and what comes out?
- Metres, centimetres, feet or inches, chosen on the Unit row, and the field label shows which one it is reading, for example Side (m). The volume comes out in the cube of that unit, with litres, US gallons and UK gallons underneath every time plus three more cubic units picked for the scale: cubic feet, cubic yards and cubic inches when you type metres, and cubic metres, cubic feet and cubic inches when you type centimetres. Switching the unit changes how your number is read rather than converting it, so 2 typed in metres becomes 2 feet the moment you press ft. Retype the side in the unit you picked.
- What happens if I type something that is not a measurement?
- The answer waits and a line under the fields says what to fix. Text gets Side needs a number, like 5, naming what you typed; zero or a negative gets Side must be greater than 0. Nothing is lost while you correct it, and a comma inside a number is fine, so 1,200 is read as one thousand two hundred rather than rejected.
Volumes are computed from the formulas shown, exact for the dimensions you type; a horizontal tank's partial fill is the exact circular-segment result. A US gallon is 231 cubic inches and a UK gallon 4.54609 litres.