Enter a radius and central angle to calculate a sector's area and arc length.
How to Use the Sector Area Calculator
Enter a radius and the sector's central angle in degrees. Area and arc length both update together.
A sector is the pie-slice wedge cut from a circle by two radii — its area is just the full circle's area scaled down by whatever fraction of 360° the angle covers:
area = (angle ÷ 360°) × π × radius²
arc length = (angle ÷ 360°) × 2π × radiusBoth formulas scale by the exact same fraction, which is why doubling the angle always doubles both the area and the arc length together — a sector's shape doesn't distort as the angle grows, it just claims a bigger slice of the same pie.