Rectangular Prism Volume Calculator: V = l × w × h

Rectangular Prism Volume

Find the volume of a rectangular prism (cuboid) by multiplying its three edge lengths. Enter length, width, and height in the same unit—centimetres, inches, metres, or feet—then read the volume in the matching cubic unit (for example cm→cm³).

Length (l)

Same unit as width and height; e.g. 12, 1.5, 100

Width (w)

Same unit as length and height

Height (h)

Same unit as length and width

Each edge length must be a positive number (greater than zero).

How it works

Find the volume of a rectangular prism (cuboid) by multiplying its three edge lengths. Enter length, width, and height in the same unit—centimetres, inches, metres, or feet—then read the volume in the matching cubic unit (for example cm→cm³).

Worked Example

Moving box in inches
A box measures 18 in × 12 in × 10 in. Volume V = 18×12×10 = 2,160 cubic inches (in³). If you had used centimetres instead, you would state V in cm³ the same way after converting edges.

Tips, Assumptions & Limitations

Use one unit for all three edges before multiplying; never mix inches and centimetres in the same calculation without converting.
Cubing the length unit names the volume: ft → ft³, m → m³.
If you know only the area of the base A and the height h, you can use V = A × h—this tool assumes you already have the three edge lengths.

FAQ

Multiply the three perpendicular edge lengths that meet at one corner: V = length × width × height. Keep every edge in the same unit so the volume lands in the matching cubic unit.

Not in one step. Convert every edge to the same unit first (for example, all centimetres or all inches), then multiply. The tool assumes your three inputs already share one unit.

Yes—names for the same shape: a box with six rectangular faces meeting at right angles. This calculator uses the prism’s three edge lengths.

Decimals are fine. Enter them as plain numbers (e.g. 2.5). The volume is still the product of all three edges.