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Circumference Calculator

The circumference is the distance once around a circle. Enter the diameter, radius or area and get the circumference in any length unit — useful for wheels, pipes, round tables, tree trunks and trim.

Quick examples
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Circumference37.6991 in
Radius
6 in
Diameter
12 in
Area
113.0973 in²

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      Formula

      Circumference = π × diameter
      Circumference = 2 × π × radius
      From area: circumference = 2 × √(π × area)

      How to use it

      1. Choose whether you know the diameter, radius or area.
      2. Enter the value and its unit.
      3. Read the circumference in the unit you need.

      Worked examples

      A 12-inch diameter: 37.70 in around, which is 0.9576 m

      Circumference
      37.6991 in
      Radius
      6 in

      A circle with a 3 m radius

      Circumference
      18.8496 m
      Area
      28.2743 m²

      A circle with an area of 50 m²

      Circumference
      25.0663 m

      A quick estimate

      Multiply the diameter by 3 and add a little under 5%. A 10-inch plate is about 31.4 inches around. For the same reason, a wheel rolls forward just over three times its diameter with each full turn.

      Questions people ask

      What is the circumference of a circle with a 10-inch diameter?

      π × 10 = 31.42 inches.

      How far does a 26-inch wheel travel in one turn?

      π × 26 = 81.68 inches, or about 6.81 feet.

      Is circumference the same as perimeter?

      Yes — circumference is simply the name for the perimeter of a circle.

      Related calculators

      Circle CalculatorRadius, diameter, circumference and area from any one of them.Diameter CalculatorDiameter of a circle from its radius, circumference or area.Radius CalculatorRadius of a circle from its diameter, circumference or area.Area of a Circle CalculatorArea of a circle from its radius, diameter or circumference.Arc Length CalculatorLength of a circular arc from its radius and central angle.Perimeter CalculatorDistance around a rectangle, triangle, circle, polygon or ellipse.