Area formula

The area of a two dimensional shape or geometric figure is the space contained within its perimeter.

Area formulas of common shapes

The exact area of many common shapes can be calculated using well-defined formulas.

Circle

The area of a circle with radius r is:

A = πr²

Triangle

The area of a triangle with base, b, and height, h, is:

If the side lengths of the triangle are given, the area can be found using:

where a, b, and c are side lengths, and

Equilateral triangle

The area of an equilateral triangle with side length, s, is:

Square

The area of a square with side, s, is:

A = s²

Rectangle

The area of a rectangle with length, l, and width, w, is:

A = lw

Parallelogram

The area of a parallelogram with base, b, and height, h, is:

A = bh

Trapezoid

The area of a trapezoid with bases, b₁ and b₂, and height, h, is:

Kite and Rhombus

The area of a kite, or rhombus, with diagonal length d₁ and d₂ is:

Regular hexagon

The area of a regular hexagon with side length s is:

Regular pentagon

The area of a regular pentagon with side length s is:

Regular octagon

The area of a regular octagon with side length s is:

Ellipse

The area of an ellipse with semi-major axis, a, and semi-minor axis, b, is:

A = πab

Area of a composite figure

Many geometric figures are made up of two or more common figures, and their areas can be calculated using a combination of the area formulas above. These types of geometric figures are referred to as composite figures.