Geometry calculator

Circumference Calculator

Find circle circumference from radius or diameter for geometry, drafting, machining, and design checks.

Use calculator View formulas FAQ

Calculator

Enter dimensions

Select a shape where available, choose units, and read the result as dimensions update.

Geometry

Radius m
Diameter m

Result

About this calculator

How it works

Circumference is the distance around a circle. The calculator can solve from radius or diameter and returns related circle values.

Formulas

Formulas used

Circumference from radius

C = 2 pi r

Circumference from diameter

C = pi d

Area

A = pi r^2

Worked example

Example: wheel with 0.35 m radius

For a circle with radius 0.35 m, the diameter is 0.70 m.

Circumference

C = 2 pi x 0.35 = 2.199 m

Area

A = pi x 0.35^2 = 0.385 m2

Guide

How to use this calculator

Select the shape or section type if a shape menu is shown.
Enter the known dimensions and choose units beside each length input.
Read the highlighted result first, then use the supporting values for related checks.

Reference

What the results mean

Circumference

The distance around the outside of the circle.

Diameter

The full width of the circle through its center.

Area

The enclosed surface inside the circle.

Assumptions and limits

Before using the result

Inputs are treated as ideal geometric dimensions with no tolerance, chamfer, fillet, draft, roughness, or manufacturing allowance.
Section properties are centroidal for the listed standard shapes and do not include rotation, offsets, or parallel-axis corrections.
Use project drawings, tolerances, material data, and applicable design standards for final engineering work.

FAQ