How do you find sector area in degrees?
A = (θ/360)πr².
Area of a Sector Calculator
Find the area of a “pie slice” of a circle using degrees or radians.
Enter radius and central angle
Choose angle unit, then provide r and θ.
About this calculator
How to use Area of a Sector Calculator, plus the formulas and logic behind the results.
Tool description
A sector is bounded by two radii and the included arc. Its area is a fraction of the full disk area.
How to use
- Select degrees or radians.
- Enter a positive radius.
- Enter the central angle.
- Select Calculate to view sector area.
Formulas & reference
Degrees: A = (θ/360) π r²Radians: A = (1/2) r² θ
Sector checks
- 60° of r=6 → A = 6π
- θ = 2π → full circle area πr²
- θ = π → semicircle area (1/2)πr²
- Arc length related: s = rθ (radians)
Calculation logic
Applies the formula matching the selected unit. Uses M_PI for the degree form.
θ should be non-negative for a conventional sector; full circle is 360° or 2π rad.
Area of a Sector Calculator FAQ
Common questions about this calculator and how to use the results.
How do you find sector area in radians?
A = (1/2)r²θ.
What is a sector?
A portion of a disk cut by two radii and the arc between them.
Can θ exceed 360°?
Mathematically the formula still scales, but angles are often reduced modulo a full turn.
Is this the same as a segment?
No. A segment is the area between a chord and its arc.
What π is used?
M_PI.