Sector Area Calculator
Calculate the area of a circular sector
Area
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Sector Area Calculator Formula
Area of a circular sector:
A = (angle / 360) × π × r²
How to Use This Calculator
- Enter the radius of the circle.
- Enter the central angle in degrees (must be between 0° and 360°, exclusive).
- Click Calculate Area to see the result.
Frequently Asked Questions
What is a circular sector?
A circular sector is a "pie slice" of a circle — the region bounded by two radii and the arc between them. The area is a fraction of the full circle's area, proportional to the central angle.
Why is 360° not allowed?
A 360° sector is just a full circle, not a sector. Use our circle calculator for that case. An angle of 0° would produce zero area, which is also not a meaningful sector.
Does this calculator use degrees or radians?
This calculator accepts the angle in degrees only. If you have an angle in radians, convert it by multiplying by 180 / π (approximately 57.2958) before entering.
What units are used?
This calculator is unit-agnostic. The result is in the square of whatever unit you use for the radius.
What is the arc length of a sector?
The arc length is L = (θ/360) × 2πr, where θ is the angle in degrees and r is the radius. This calculator computes area only; use the arc length formula separately if needed.
Can I share my calculation?
Yes. After clicking Calculate, the URL updates with your input values. Copy and share the URL to let anyone else see the same pre-filled form and result.