Use this geometry calculation when the shape, dimensions, coordinate system, and units match the stated ideal Euclidean model.

Radius

Required number input.

Compute circumference of a circle as 2*pi*r. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Circumference

The resulting circumference returned as a number.

• The result assumes exact idealized geometry. Measurement uncertainty, rounded inputs, nonplanarity, self-intersection, thickness, curved coordinate systems, and ambiguous dimension definitions are not automatically represented.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Sketch and label the dimensions, verify unit consistency, and use coordinate or CAD methods for irregular measured shapes.

• Circle Calculator

  Calculate a circle's radius, diameter, circumference, and area from one known measurement.

• Chord Length Calculator

  Compute the chord length subtended by a central angle in a circle.

• Circle Arc Length Calculator

  Compute the arc length of a circular segment from its central angle and radius.