Arc length and sector area from radius and angle.. Arc Length Calculator is a free online tool from the ToolsRift Math Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Loading Arc Length Calculator…
How to use Arc Length Calculator
Enter the radius and the central angle and the calculator returns the arc length and the sector area with formulas shown.
Frequently asked questions
How is arc length calculated?
Arc length = r × θ when θ is in radians, or (θ/360) × 2πr when θ is in degrees.
What is the sector area formula?
Sector area = (θ/360) × πr² in degrees, or ½ × r² × θ in radians.
Do I enter the angle in degrees or radians?
You can use degrees — the calculator handles the conversion and shows both the arc length and sector area.
ToolsRift processes your files in your browser. We use cookies only for basic analytics and to support ads that keep every tool free. See our Cookie Policy.