Sector Area Calculator
Enter a circle's radius and a central angle in degrees; this calculator returns the sector area as (angle divided by 360) times pi times radius squared. A radius of 5 and a 90-degree angle give a sector area of 19.635.
What this calculator does
The Sector Area Calculator estimates your result instantly from the values you enter, using standard math & conversions formulas. Enter a circle's radius and a central angle in degrees; this calculator returns the sector area as (angle divided by 360) times pi times radius squared. A radius of 5 and a 90-degree angle give a sector area of 19.635. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.
Result
About Sector Area Calculator
The Sector Area Calculator finds the area of a circular sector (a pie slice) from a radius and a central angle in degrees, using (angle / 360) × π × r².
Formula & Mathematical Calculation
Sector Area = f(Radius, Central Angle (degrees))
Calculated according to standard math formulas implemented in the calculator core.
Calculation Example
Enter Radius 5 and Central Angle 90 degrees, then click Calculate. The tool shows Sector Area: 19.635, with the note 'Sector area = (angle/360) x pi x r^2 = 19.635.'
Key Benefits
- Computes a circular sector's area from radius and angle
- Takes the central angle in degrees, not radians
- Uses the (angle over 360) times pi times r squared formula
- Rejects a negative radius
How to Use this Calculator
-
Enter radius and angle
Type the radius and the central angle in degrees. -
Calculate
Click Calculate. -
Read the area
Read the Sector Area box.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
- Results use standard published formulas and account only for the values entered above.
- Rounding is applied for display; the underlying calculation uses your full precision.
- Results are returned in the same units you enter, unless the tool states the output unit.
What it does not cover
- Sector Area Calculator produces a calculated result for reference and learning, not a certified or official measurement.
- Real-world outcomes differ when tolerances, rounding rules or local standards apply.
- Definitions and standards vary by region and change over time; verify the convention that applies to your case.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For work where the result carries real consequences, confirm it against an authoritative source.
Frequently Asked Questions
Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.