Area of a Circular Sector Calculator
A = ½ r² θ (radians) or A = πr² × (θ/360) (degrees).
Result
General calculation reads
Amazon affiliateAs an Amazon Associate we may earn from qualifying purchases. This does not add cost for you.
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?+
Related calculators
More tools you might like
Hand-picked tools that pair well with this one — same audience, same intent.
Calculate the area of a circle given its radius (or diameter). A = πr².
A = π × a × b, where a and b are the semi-major and semi-minor axes.
A = ¼ × n × s² × cot(π/n) for an n-gon with side length s.
C = 2πr (or πd). Area = πr². The fundamental circle formulas.
V = (4/3)πr³. Surface area = 4πr².
Estimate body surface area in m² using Mosteller and Du Bois formulas — for clinical reference, anesthesia dosing, and physiologic indexing.