What this calculator does
A flat rectangle has no volume of its own, since it is a two-dimensional shape with no depth. When people search for the volume of a rectangle they almost always mean a rectangular box, also called a cuboid or rectangular prism: a three-dimensional shape with a rectangular base extended upward by a height.
The volume of a rectangular box is simply length times width times height. It is the most common volume calculation there is, covering everything from a shipping carton to a room to a garden bed, and it needs nothing more than three straight-line measurements.
The formula
Multiply the length by the width to get the base area, then multiply that by the height. The result is the volume in cubic units matching whatever unit the three measurements were taken in.
| Term | Meaning |
|---|---|
| V | Volume, in cubic units. |
| Length and width | The two side lengths of the rectangular base. |
| Height | The third dimension, at right angles to the base, sometimes called depth. |
The inputs explained
| Field | What to enter |
|---|---|
| Length | The length of the box. |
| Width | The width of the box. |
| Height | The height (or depth) of the box. |
When to use it
Working out how much a box, tank or room holds
A storage container, water tank, raised garden bed or room all reduce to the same box-volume calculation once their length, width and height are measured.
Converting to litres for liquid capacity
Measuring dimensions in centimetres and dividing the resulting cubic-centimetre volume by 1,000 gives capacity in litres, which is how a tank or container is usually rated.
Comparing two box sizes before buying
Two boxes with the same footprint but different heights, or the same height but different footprints, can hold very different volumes; working out both figures directly settles which one is actually bigger inside.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How volume changes as width increases at a fixed length and height
A fixed length of 10 and height of 4, across a range of widths.
| Width | Volume | Surface area |
|---|---|---|
| 2 | 80.000 | 136.000 |
| 4 | 160.000 | 192.000 |
| 6 | 240.000 | 248.000 |
| 8 | 320.000 | 304.000 |
| 10 | 400.000 | 360.000 |
| 12 | 480.000 | 416.000 |
How volume changes with height at a fixed footprint
A fixed base footprint of 10 by 6, across a range of heights.
| Height | Volume | Surface area |
|---|---|---|
| 2 | 120.000 | 184.000 |
| 4 | 240.000 | 248.000 |
| 6 | 360.000 | 312.000 |
| 8 | 480.000 | 376.000 |
| 10 | 600.000 | 440.000 |
| 12 | 720.000 | 504.000 |
Questions
Is "volume of a rectangle" the correct term?
Strictly no, since a rectangle is flat and has no volume. The calculation people are after is the volume of a rectangular box, also called a cuboid or rectangular prism, which is what this calculator computes.
Does the order of length, width and height matter?
No. Multiplication is commutative, so length times width times height gives the same result no matter which dimension is labelled which, as long as all three measurements are in the same unit.
How do I get the volume in litres?
Measure length, width and height in centimetres, multiply them together for a volume in cubic centimetres, then divide by 1,000. This calculator shows that conversion automatically.
What if my box has a lid or open top?
That affects surface area, since an open box has one fewer face to cover, but it makes no difference to the volume calculation, which only depends on the internal length, width and height.
For a wider set of shapes including spheres, cylinders and cones, see the volume of common shapes calculator. For a pyramid built on a rectangular base instead of a box, see the rectangular pyramid volume calculator.