Area: Quantity that expresses the extent of a two-dimensional surface or shape, or planar lamina, in the plane

It is useful because it is how much of a material is needed to make a hollow container. Area is the amount of surface covered by a close object or shape.

Some units used to measure area are square foot, square mile, square metre and square kilometre. The area of a planar figure is often written as ${\displaystyle A}$. Areas of regular shapes such as square, rectangle, triangle and circle can be calculated through formulas. The area of an irregular shape can be approximated through grid or graph paper.

One can use different formulas to find the area of different shapes. For example:

• Area of a rectangle is the length of any two touching sides multiplied together. In other words, length times width.
• Area of a triangle is half of the base multiplied by the perpendicular height. In other words, ${\displaystyle A={\tfrac {1}{2}}bh}$.
• Area of a circle: ${\displaystyle A=\pi r^{2}}$

The area of a flat object is related to the surface area and volume of a three-dimensional object.

The area under a curve can be found using integration, a concept from calculus.

• Mu (unit of area)