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Switch tool with the current settings for radius, and calculate circle circumference, circle diameter, sphere volume or sphere surface area instead

## Related Tools

- Calculate radius of circle from area
- Circle radius to circumference calculator
- Circle radius to diameter calculator
- Convert an area to different units
- Length and distance converter
- Sphere radius to volume calculator
- Sphere radius to surface area calculator

## User Guide

This tool will calculate the area of a circle from the radius, and will convert different measurement units for radius and area.

### Formula

The formula used to calculate circle area is:

A = π · r^{2}

#### Symbols

- A = Circle area
- π = Pi = 3.14159…
- r = Circle radius

### Radius of Circle

Enter the radius of a circle. The radius is the distance between the centre and any point on the outer edge of a circle.

### Area of Circle

This is the area contained within a circle with the specified radius.