Area of a Circular Sector Calculator
A = ½ r² θ (radians) or A = πr² × (θ/360) (degrees).
Result
How to use this calculator
- Enter the radius.
- Enter the central angle in degrees or radians.
- Read sector area and arc length.
About this calculator
A sector is a "slice" of a circle bounded by two radii and an arc. The area is a fraction of the full circle proportional to the central angle. In radians the formula is A = ½r²θ; in degrees it's A = πr² × (θ/360). Arc length is r × θ (radians).
Frequently asked
Why does the formula change with the unit?+
What is the area of a semicircle?+
How does sector area relate to a pie chart?+
Can the angle exceed 360°?+
What is the arc length for the sector?+
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