## The Lesson

The area of a circle is found using the formula:

In this formula, r is the radius of the circle. The image below shows what we mean by radius:

## How to Find the Area of a Circle

Finding the area of a circle is easy.

## Question

What is the area of a circle with a radius of 5 cm, as shown below?

# 1

Area = πr2
Don't forget: π is pi (≈ 3.14) and r2 = r × r (r squared).

# 2

Substitute the radius into the formula. In our example, r = 5.
Area = π × 52 = π × 5 × 5 = 78.5 cm2

The area of the circle with a radius of 5 cm is 78.5 cm2.

## "Find the Area" Widget

Here is a widget to help you learn the formulas to find the areas of different shapes.

## Lesson Slides

The slider below shows another real example of how to find the area of a circle. Open the slider in a new tab

## How to Find the Area of a Circle Using the Diameter

The area of a circle can be found using the diameter rather than the radius. The area of a circle, using the diameter, is found using the formula:

In the formula, d is the diameter of the circle. The image below shows what we mean by diameter:

Read more about how to find the area of a circle using the diameter

## What Is a Circle?

A circle is a shape containing a set of points that are all the same distance from a given point, its center.