Area of a Circle
Calculate the area of a circle using A = πr².
Learn how to find the area from the radius or diameter with step-by-step examples.
The Formula
A = πr²
This formula calculates the area enclosed by a circle.
If you know the diameter instead, use r = d / 2 first.
Variables
| Symbol | Meaning |
|---|---|
| A | Area of the circle |
| π | Pi, approximately 3.14159 |
| r | Radius — the distance from the center to the edge |
Example 1
Find the area of a circle with radius 7 cm
A = πr² = π × 7²
A = π × 49
A ≈ 153.94 cm²
Example 2
A circular garden has a diameter of 12 meters. What is its area?
Diameter = 12 m, so radius = 12 / 2 = 6 m
A = πr² = π × 6²
A = π × 36
A ≈ 113.10 m²
When to Use It
Use the area of a circle formula when:
- Calculating the surface area of circular objects (plates, wheels, tables)
- Determining how much material is needed to cover a circular area
- Comparing the size of circles with different radii
- Working with circular cross-sections in engineering or science