Perimeter of a Circle Calculator

Summary

Enter a radius or diameter to instantly calculate the circumference of a circle with step-by-step working.

How it works

1. Choose whether to enter the radius or the diameter.
2. Type the measurement value in the input field.
3. Select your preferred unit (mm, cm, m, in, or ft).
4. Click "Calculate" to apply the formula C = 2πr (or C = πd).
5. The circumference result appears with step-by-step working.

Use cases

• Geometry homework involving circle measurements.
• Finding the length of fencing needed around a circular garden.
• Calculating the tread of a wheel or tire for a given diameter.
• Engineering problems requiring the circumference of circular pipes or shafts.
• Verifying manual circumference calculations quickly.
• Estimating material needed for circular frames or borders.

Frequently Asked Questions