What is the Sector Area Calculator?
Find the area and arc length of a sector of a circle.
Enter radius and central angle and the Sector Area Calculator returns sector area, arc length and chord length. Results update as you type, and nothing you enter leaves your device.
How it is calculated
Sector area = θ ÷ 360 × πr²
Arc length = θ ÷ 360 × 2πr
How to use it
- Enter radius.
- Enter central angle in °.
- Read sector area in the results panel. It updates as you type.
- Change any value to compare scenarios, or use Share to send the result as a link.
Worked example
Common questions
What formula does the Sector Area Calculator use?
It uses: Sector area = θ ÷ 360 × πr²; Arc length = θ ÷ 360 × 2πr.
What do I need to use the Sector Area Calculator?
You need radius and central angle. Sensible starting values are filled in so you can see how it works straight away.
Is the Sector Area Calculator free, and is my data stored?
It is free with no sign-up. The calculation runs in your browser, so the values you enter are not sent to or stored on our server.