Area of a parallelogram

The number of square units it takes to completely fill a parallelogram.
Formula: Base × Altitude
Try this Drag the orange dots to move and reshape the parallelogram. Drag point D to change the base.

Area formula

The area of a parallelogram is given by the formula where
b is the length of any base
a is the corresponding altitude

See Derivation of the formula.

Recall that any of the four sides can be chosen as the base. You must use the altitude that goes with the base you choose. The altitude (or height) of a parallelogram is the perpendicular distance from the base to the opposite side (which may have to be extended). In the figure above, the altitude corresponding to the base CD is shown.

Things to try

  1. In the figure above, click on "hide details"
  2. Drag the orange dots on the vertices to make a random-size parallelogram.
  3. Estimate the area of the parallelogram just counting the squares inside it
  4. Calculate the area using the formula
When you done, click "show details" to see how close you got.

Other polygon topics


Types of polygon

Area of various polygon types

Perimeter of various polygon types

Angles associated with polygons

Named polygons