Arc Length Calculator
Calculate arc length from radius and central angle.
How to Use the Arc Length Calculator
Enter the circle radius and central angle to calculate the length of the corresponding arc.
Practical Example
With radius 8 and angle 90°, the arc is one quarter of the circumference, about 12.57 units long.
Factors That Affect the Result
Use the angle unit expected by the tool and a consistent radius unit. Larger angles or radii produce longer arcs.
Frequently Asked Questions
What is arc length?
It is the distance along part of a circle’s circumference.
Can I use radians?
Only if the tool specifically expects radians; otherwise enter degrees.
What units are returned?
The same linear unit used for the radius.
Related Tools
- Sector Area Calculator
- Circle Segment Calculator
- Chord Length Calculator
- Circle Calculator
- Area Calculator
Interpreting Arc Length
Arc length measures only part of a circle’s circumference. With an angle in degrees, the common formula is (angle ÷ 360) × 2πr. Radius and output use the same linear unit, while the central angle controls what fraction of the circle is included.
This is useful for curved paths, sectors, fabrication layouts and geometry work. Make sure the angle unit matches the formula; radians use a different expression. Rounding the radius or angle too early can noticeably change the final length.