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).
Same unit as width and height; e.g. 12, 1.5, 100
Same unit as length and height
Same unit as length and width
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).
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.
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.
Rectangular Prism Volume Calculator: The l × w × h Box Formula
The volume of a rectangular prism is one of the most common “multiply three numbers” jobs in school maths. This article explains the idea in plain language, shows a quick worked example, and points to a free calculator that follows the same steps you would write by hand.
Treat the shape as a box: pick one corner and read off how far you travel along each of three perpendicular directions—often called length, width, and height. Volume counts how many unit cubes (1 cm × 1 cm × 1 cm, or 1 in × 1 in × 1 in, and so on) fit inside. Multiplying the three edge lengths answers that count, which is why V = l × w × h is the standard formula. The only discipline students forget most often is consistency: every edge must use the same measuring stick before you multiply, especially when lessons hop between metric classrooms and imperial rulers.
Let l, w, and h be positive lengths measured in the same unit. Then the volume is V = l × w × h, reported in cubic units (for example cm³ if the edges were centimetres).
Picture a small packing crate labelled 0.8 m by 0.5 m by 0.6 m. Multiply in metres first: V = 0.8 × 0.5 × 0.6 = 0.24 m³. If a problem gives inches instead, keep all three numbers in inches, multiply, and state cubic inches; convert first when a worksheet asks for a specific unit system.
Open the rectangular prism volume calculator and type the three edge lengths into the length, width, and height boxes—using the same unit for each field. Press calculate to see the line-by-line product. Read the final line as your volume in cubic units that match the edges you chose (cm→cm³, ft→ft³, etc.). If you see an error message, check for blank fields, letters accidentally typed in the boxes, zeros or negative values, or mixed units that still need converting.
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