Area of a Parallelogram Formula

Geometry Formulas: Area, Volume, Perimeter
Formula:

What is the formula for the area of a parallelogram?

Answer

Area of a parallelogram
A = a · h

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

Where the formula comes from

A = a · h

Cut the triangle off one end of the parallelogram and move it to the other end: what is left is a rectangle of base a and height h. Nothing was added or removed, so the areas are equal.

Worked examples

Let a = 9, h = 5. Then the area of a parallelogram = 45 square units.

Let a = 6.4, h = 3. Then the area of a parallelogram = 19.2 square units.

The common mistake

Multiplying the two sides. A parallelogram is not a rectangle: the second side is longer than the height, and using it inflates the area. Only the perpendicular height counts.

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 area of a parallelogram? (The answer is: A = a · 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 (h = 5)

If a =Area
15 square units
210 square units
315 square units
420 square units
525 square units
1050 square units

FAQ

What is the formula for the area of a parallelogram?

Area of a parallelogram A = a · h

Where does this formula come from?

Cut the triangle off one end of the parallelogram and move it to the other end: what is left is a rectangle of base a and height h. Nothing was added or removed, so the areas are equal.

What is the most common mistake here?

Multiplying the two sides. A parallelogram is not a rectangle: the second side is longer than the height, and using it inflates the area. Only the perpendicular height counts.

How do I use this formula?

Put your own numbers in place of the letters. With a = 6.4, h = 3, for instance, the formula A = a · h gives = 19.2 square units.