Enter the arc length and radius into the calculator to evaluate and determine the central angle of the circle contained in that arc.

- Arc Length Calculator
- Double Angle Calculator
- Coterminal Angle Calculator
- Interior Angle Calculator
- Exterior Angle Calculator
- Arc Height (sagitta) Calculator

## Central Angle Formula

The following equation is used to calculate a central angle contained by a circular arc.

C = L / r

- Where C is the central angle in radians
- L is the arc length
- r is the radius

## Central Angle Definition

A central angle is an angle contained between a radius and an arc length. In other words, the angle of rotation the radius needs to move in order to produce the given arc length.

## Central Angle Example

How to calculate a central angle?

**First, determine the arc length.**Measure or calculate the length of the arc.

**Next, determine the radius.**Measure the length of the radius.

**Finally, calculate the central angle.**Using the equation above, calculate the central angle.

## FAQ

**What is a central angle?**

A central angle is an angle contained by a portion of an arc defined by an arc length and radius. It’s sometimes referred to as the angle of rotation of an arc.

**What is an arc length?**

An arc length is the measure of the distance along an arc contained by a radius and angle.