Circle Circumference Calculator

Calculate the circumference of a circle using its radius or diameter. Simply enter your measurement, choose the unit, and get instant results.

How to Use This Calculator

  1. Choose whether you want to input the radius or diameter
  2. Enter your measurement value
  3. Select your preferred unit (mm, cm, m, km, in, ft, yd, or mi)
  4. Click "Calculate" to get the circumference

Formula: Circumference = 2 × π × radius or Circumference = π × diameter

This tool calculates a circle's circumference when you provide the radius or diameter. It is ideal for students, teachers, and professionals.

How to Use This Tool

  1. Select whether you want to enter the radius or diameter.
  2. Type a positive number in the input field.
  3. Click the Calculate button or press Enter.

Explanation of Input Fields

The first dropdown lets you choose between radius and diameter. The label next to the number field changes based on your choice. When you type a number, the tool uses it to compute the circumference. The number must be positive.

Interpreting the Output

The tool shows four values. These include the circumference, diameter, radius, and area. The circumference is computed with the formula 2 x Pi x Radius. Each value is rounded off appropriately. The output uses the unit you see in the result.

Limitations and Special Notes

If you enter an invalid value, you get an error message. The tool rounds off numbers based on their size. Small numbers may use more decimals. The tool provides quick results without lengthy instructions.

Common Use Cases

This calculator helps in many situations. It is useful for homework tasks in geometry. It also works well for simple design projects. Professionals find it handy during planning and review processes.

Additional Formula Information

Remember, the formula is 2 x Pi x Radius. This helps you understand the math behind the result.