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Circle Circumference calculator

Calculate the distance around a circle from its radius.

How it works Report a problem

Circle Circumference calculator

Enter your values below and press Calculate to see your result instantly.

C = 2π×
Radius Vector (r)
Computed Absolute Circumference (C)
31.42 Units
SPHERICAL AREA (A)
78.54 Units²
DIAMETER DEVIATION
10 Units
r=5
Calculations complete.

About the Circle Circumference calculator

Calculate the distance around a circle from its radius.

How to use the Circle Circumference calculator

  1. Enter the Radius (r).
  2. Press Calculate.

Formula and method

C = 2 × π × r, which is also π × d.

Worked example

A radius of 5 gives a circumference of 31.42 units and an area of 78.54.

Tips

  • Use the same units for the answer as for the radius.

Frequently asked questions

How do I find the circumference from the diameter?
Multiply the diameter by π.