Measure the distance around any circle by entering its radius or diameter. The circumference equals 2 times pi times the radius, or equivalently pi times the diameter, so a circle with radius 5 has a circumference of about 31.42. This calculator updates the moment you change a value and also shows the diameter and area so you have the full picture at once. Circumference is the perimeter of a circle and shows up when you fence a round pond, wrap a ribbon around a jar, size a bike wheel, or work through geometry problems. The answer uses the same units you enter, so a radius in inches returns a circumference in inches. All math happens locally in your browser using the high precision value of pi built into JavaScript, and you can copy the answer with one click.
The circumference is 2 times pi times the radius, the distance all the way around the circle.
Yes. Since the diameter is twice the radius, the circumference also equals pi times the diameter.
Circumference is the distance around the circle while area is the space inside it, and they use different formulas.
Measure the distance around any circle by entering its radius or diameter. The circumference equals 2 times pi times the radius, or equivalently pi times the diameter, so a circle with radius 5 has a circumference of about 31.
Yes. Circle Circumference Calculator is completely free, with no sign-up and no usage limits.
Yes. Circle Circumference Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Circle Circumference Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.