Sector Area Calculator
Calculate the area of a circle sector from its radius and angle in degrees or radians instantly with this free browser-based sector area calculator.
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Shape
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How to use this calculator
- Enter the radius and angle.
- Press Calculate.
How it works
Area of a pie slice = (angle ÷ 360) × π × radius².
Worked example
radius 2 m, 90°. ≈ 3.14 m².
Common mistakes
- Mixing degrees and radians — match the formula to your angle unit.
- Confusing the sector (a pie slice) with the segment (cut off by a chord).
Frequently asked questions
How do I find the area of a sector?
Area = (angle ÷ 360) × πr² for degrees, or ½ × r² × angle for radians — the fraction of the circle the slice covers.
What's the difference between a sector and a segment?
A sector is a pie slice bounded by two radii and the arc; a segment is the smaller area cut off by a straight chord and the arc.
Related tools
- Arc Length Calculator
- Circle Area Calculator
- Circle from Diameter Calculator
- Circumference Calculator
- Annulus Area Calculator
- Cone Surface Area Calculator
Explore more in Geometry, Shape, Area & Volume.
Cite this tool
Zerdly. (2026). Sector Area Calculator. Retrieved from https://www.zerdly.com/tools/sector-area-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.