A crate 2 m by 1.5 m by 1 m
Three cubic metres, or 3 000 litres. The longest diagonal is about 2.69 m, which is what decides whether it fits through a doorway.
The surface area of 13 m² is the figure to use for wrapping, painting or insulating it.
Volume calculator
Result
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How it works
Volume is area carried through a third dimension. A box is a rectangle pushed upwards; a cylinder is a circle pushed upwards; a triangular prism is a triangle pushed sideways. In each case the rule is the same: work out the cross-section, then multiply by how far it travels.
Cones and pyramids are the exception, and share the same surprising factor. Each holds exactly a third of the box or cylinder that would enclose it, whatever the shape of the base. It is the reason a conical heap of sand looks so much smaller than the bucket it came from.
Spheres follow their own rule, four thirds of pi times the radius cubed — and the cube is what makes size so deceptive. A ball twice the diameter holds eight times as much, which is why one large scoop of ice cream beats two small ones.
Formulas used
Prisms and cylinders
V = base area × height
Cones and pyramids
V = base area × height ÷ 3
Sphere and capsule
V = 4 ÷ 3 × π r³ V = π r² L + 4 ÷ 3 × π r³
A capsule is a cylinder with a hemisphere on each end, which together make one whole sphere.
Worked examples
A cylindrical tank, 1 m across and 2 m tall
A radius of 0.5 m gives about 1.571 m³, or roughly 1 571 litres.
Widening the tank matters far more than raising it: adding 20% to the radius adds 44% to the capacity, while adding 20% to the height adds only 20%.
An aquarium in centimetres
Eighty by thirty-five by forty-five centimetres comes to 126 litres — before gravel, rocks and the gap you leave at the top.
Water weighs about a kilogram per litre, so this tank alone puts 126 kg on whatever it stands on.
Assumptions and limits
- Solids are regular and hollow-free.
- The capsule’s straight section excludes the two rounded ends.
- Pyramid and cone heights are vertical, not measured along a face.
- Capacity assumes the solid is filled completely.
Frequently asked questions
How many litres are in a cubic metre?
Exactly 1 000. The litre was defined as a cubic decimetre, and there are ten decimetres to a metre in each of three directions.
The same logic gives 1 000 cubic centimetres to a litre, which is why a millilitre and a cubic centimetre are the same thing.
Why does doubling the radius multiply the volume by eight?
Because the radius appears three times in the formula — once for each dimension. Doubling it doubles the width, the depth and the height at once, and 2 × 2 × 2 is 8.
It works in reverse too: halving a sphere’s diameter leaves it holding an eighth of what it did.
How much concrete should I order?
Work out the volume of the pour, then add for waste — usually 5 to 10% for a simple slab, more if the ground is uneven or the formwork is complicated.
Concrete is sold by the cubic metre or cubic yard, and running out halfway through a pour is far more expensive than a little surplus.
Which gallon is which?
A US gallon is 3.785 litres; an imperial gallon is 4.546 litres, about 20% larger. Both appear in the conversion table, kept separate.
Vehicle and tank specifications rarely say which they mean, so check the origin of the figure before converting it.
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