Volume of a Rectangular Prism Formula

Geometry Formulas: Area, Volume, Perimeter
Formula:

What is the formula for the volume of a rectangular prism?

Answer

Volume of a rectangular prism
V = a · b · h

Here a is the side (or base), b is the second side, h is the height, perpendicular to the base. The result comes out in cubic units.

Where the formula comes from

V = a · b · h

The base is a rectangle of area a·b, and the solid is that rectangle repeated to a height h. Base times height, the same rule as the cylinder — only the base is easier to draw.

Worked examples

Let a = 5, b = 4, h = 3. Then the volume of a rectangular prism = 60 cubic units.

Let a = 2.5, b = 6, h = 1.2. Then the volume of a rectangular prism = 18 cubic units.

The common mistake

Reporting the answer in square units. Three lengths multiplied give a cube: metres × metres × metres is m³, not m².

Other quantities: Rectangular prism

See Also

Geometry Formulas: Area, Volume, Perimeter

These are the formulas for the area, perimeter, circumference, volume and surface area of the standard shapes — 31 of them. Each page shows not only the formula but where it comes from, what every letter stands for, two worked examples and the mistake that this particular shape invites. For example, it can help you find out what is the formula for the volume of a rectangular prism? (The answer is: V = a · b · h). Pick the pair — "Area of a circle", for instance — and hit the "Find out" button.
Geometry Formulas: Area, Volume, Perimeter
Formula:

Values from the Formula (b = 4, h = 3)

If a =Volume
112 cubic units
224 cubic units
336 cubic units
448 cubic units
560 cubic units
10120 cubic units

FAQ

What is the formula for the volume of a rectangular prism?

Volume of a rectangular prism V = a · b · h

Where does this formula come from?

The base is a rectangle of area a·b, and the solid is that rectangle repeated to a height h. Base times height, the same rule as the cylinder — only the base is easier to draw.

What is the most common mistake here?

Reporting the answer in square units. Three lengths multiplied give a cube: metres × metres × metres is m³, not m².

How do I use this formula?

Put your own numbers in place of the letters. With a = 2.5, b = 6, h = 1.2, for instance, the formula V = a · b · h gives = 18 cubic units.