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

## Related Tools

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

## User Guide

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

### Formula

The formula used to calculate circle area is:

A = π · (ø/2)^{2}

A = ¼ · π · (ø/2)^{2}

#### Symbols

- A = Circle area
- π = Pi = 3.14159…
- ø = Circle diameter

### Diameter of Circle

Enter the diameter of a circle. The diameter of a circle is the length of a straight line drawn between two points on a circle where the line also passes through the centre of a circle, or any two points on the circle as long as they are exactly 180 degrees apart.

### Area of Circle

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