Circumference Calculator
Calculate the circumference and area of a circle from its radius or diameter, free and instant right in your browser.
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Shape
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How to use this calculator
- Enter the radius.
- Press Calculate for the circumference, diameter and area.
How it works
The circumference of a circle is 2 × π × radius. The diameter is 2 × radius, and the area is π × radius².
Worked example
Radius 1 m. Circumference = 2 × π × 1 = 6.2832 m.
Frequently asked questions
What's the difference between circumference and perimeter?
They're the same idea — circumference is the name for a circle's perimeter, the distance all the way around it.
Can I work it out from the diameter?
Yes: circumference = π × diameter. Since diameter = 2 × radius, both formulas give the same answer.
Related tools
- Circle Area Calculator
- Cylinder Volume Calculator
- Sector Area Calculator
- Arc Length Calculator
- Circle from Diameter Calculator
- Hemisphere Volume Calculator
Explore more in Geometry, Shape, Area & Volume.
Cite this tool
Zerdly. (2026). Circumference Calculator. Retrieved from https://www.zerdly.com/tools/circumference-calculator/
Tip: Enter any known values to calculate the remaining results.
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