How to Use the Arc Length & Sector Area Calculator
Whether you're sizing up a slice of pizza, a fan-shaped garden bed, or a curved stretch of road, this calculator finds the size of a piece of a circle. Just enter the radius and the central angle (how wide the slice opens), and it returns both the arc length and the sector area at once. The central angle field supports both degrees and radians, so you can type in whatever unit your source data uses.
The underlying formulas run on radians. Once the central angle is converted to radians, arc length = radius × radians and sector area = ½ × radius² × radians. If you enter degrees, the calculator automatically converts using 'degrees × π ÷ 180' before running the formulas, so there's no manual conversion needed on your end.
A central angle can never exceed a full circle, so degree inputs are capped at 360 and radian inputs at 2Ï€ (about 6.283). Entering a value beyond that range falls outside the definition of a sector, so the calculator shows an error instead of a misleading result.
Frequently Asked Questions
Pick degrees or radians from the unit selector and enter the matching central angle value. The calculator converts to radians automatically before computing.
A full circle only goes up to 360 degrees (2Ï€ radians), so any value beyond that falls outside the definition of a sector and can't be calculated.