FREE BROWSER TOOLGeometry
Arc Length and Sector Area Calculator
Enter a radius and the angle swept by a slice of a circle. The arc length measures the curved edge. The sector area measures the surface enclosed by that edge and the two radii.
Calculations run in your browser. No account or API key is needed.
Your result
Edit inputs- Arc length
- 9.424777961 cm
- Sector area
- 28.27433388 cm²
Arc length = 9.424777961 cm Sector area = 28.27433388 cm² r = 6 cm θ = 1.570796327 rad
How to use this tool
Measure from the center to the curved edge and choose the length unit.
Enter the angle at the center in degrees or decimal radians, up to one full turn.
Update the result to read the curved edge length and area of the sector.
Cut a quarter circle
A 90° sector with a 6 cm radius uses one quarter of a circle. Its curved edge measures 3π cm, about 9.42 cm. Its face covers 9π cm², about 28.27 cm². For the distance all the way around this cutout, add the two 6 cm straight edges.
Calculate with radians
Multiply an angle in degrees by π / 180 to get the angle θ in radians. The arc length is rθ and the sector area is r²θ / 2. Values displayed here use up to ten significant digits.
Common questions
How do I measure the longer arc between two points?
Use the angle that sweeps through the longer arc. For two radii 60° apart, the shorter arc uses 60° and the longer one uses 300°.
What angle gives a complete circle?
Use 360° or 2π radians, approximately 6.283185307179586. At one full turn the arc length equals the circumference and the sector covers the whole disk.