Circle measurements

Enter a measured radius and keep both common circle formulas visible. The sample uses a radius of 3.5 metres.

How it works

1. Replace radius with the measurement from your drawing or object.
2. Review area for the surface inside the circle.
3. Use circumference for the distance around its edge.

Try changing the unit to centimetres or inches and let the result keep the corresponding square unit for area.

Next: solve a quadratic in simple steps