Calculate angular displacement from arc length and radius.
Last updated: June 2026 | By Patchworkr Team
Angular displacement is the angle swept out by an object moving along a circular path. It tells you how far something has rotated, not how far it has traveled in a straight line.
Arc length and radius are the key pieces of the formula because the larger the radius, the more distance is needed to produce the same angle. That relationship is what makes angular displacement useful in circular motion, geometry, and physics.
In radians, angular displacement is especially convenient because one radian is defined directly from the circle itself: when the arc length equals the radius, the angle is 1 radian.
Arc length measures the distance traveled along a circular path, while angular displacement measures the amount of rotation. Two objects can travel different arc lengths but still have the same angular displacement if their circles have different radii.
That distinction matters because the calculator converts distance into rotation by dividing the arc length by the radius. The result is the angle, not the path length itself.
Angular displacement can be expressed in radians, degrees, or revolutions. Radians are often preferred in mathematics and physics because they connect directly to arc length through the relationship theta = s / r.
Degrees are more familiar in everyday measurements, while revolutions describe complete turns around a circle. The calculator shows all three so you can use the unit that fits your problem best.
The calculator uses theta = s / r, where s is arc length and r is radius. Once the angle is found in radians, it can be converted into degrees or revolutions.
A smaller radius would produce a larger angle for the same arc length, while a larger radius would produce a smaller angle. That is why the radius matters as much as the distance traveled.
What if radius is zero?
The angle is undefined because there is no circular path.
Can angular displacement be negative?
Yes. Direction determines the sign.
Does it support degrees?
Yes. You can choose radians, degrees, or revolutions.
What is the formula?
Angular displacement in radians is arc length divided by radius.
Related Tools
Convert angle formats.
Double angle formulas.
Half angle formulas.
Calculate hyperbolic functions.
Calculate inverse trig functions.
Apply law of cosines.