Arc Length Calculator | Find Arc of a Circle Online

Arc Length

Find the length of a curved part of a circle's circumference with this easy-to-use Arc Length Calculator. Just enter the radius and central angle in degrees.

Radius (r)

The distance from the center to the edge of the circle.

Central Angle (θ) in Degrees

The angle subtended by the arc at the center of the circle.

How it works

Find the length of a curved part of a circle's circumference with this easy-to-use Arc Length Calculator. Just enter the radius and central angle in degrees.

The Formula

Arc Length = (Angle / 360°) × 2πr

Worked Example

Calculate Arc Length
Imagine a circle with a radius of 5 cm. If the central angle is 90 degrees, the arc length would be (90/360) * 2 * π * 5 = (1/4) * 10π = 2.5π ≈ 7.85 cm.

Tips, Assumptions & Limitations

Ensure your angle is in degrees if using the 360° formula. To convert radians to degrees, multiply by 180/π.
The arc length is a portion of the circle's total circumference.

FAQ

Circumference is the total distance around the entire circle, while arc length is the distance along just a portion of that circle's edge.

Our calculator currently takes the angle in degrees. If you have an angle in radians, multiply it by 180/π to convert it to degrees first before entering it into the tool.

Pi is a fundamental constant in circle geometry, representing the ratio of a circle's circumference to its diameter. Since arc length is a part of the circumference, Pi naturally appears in its formula.