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## Related Tools

- Calculate diameter of circle from radius
- Circle area calculator using diameter
- Circle circumference calculator using diameter
- Length and distance converter
- Sphere volume calculator using diameter
- Sphere diameter to surface area calculator

## User Guide

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

### Formula

The formula used to calculate circle radius is:

r = ø / 2

#### Symbols

- r = Circle radius
- 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.

### Radius of Circle

This is the radius of a circle that corresponds to the specified diameter. The radius is the distance between the centre and any point on the outer edge of a circle.