# Circle Area & Circumference Calculator from Radius

Would you like to know the area or the circumference of a circle and the only piece of information you have is the radius of the circle? Use our Circle Area & Circumference Calculator from Radius calculator that gives you the circumference and the area of a circle – the only thing you have to enter is the radius of the circle.

## Circle Area & Circumference Calculator from Radius

The use of the calculator is easy: enter the radius of the circle, then click on the Calculate button. The result appears immediately. If you want to run the calculation for another circle, enter the new radius and click on the Calculate button again.
(In the unit the radius had been entered. If, for example, the radius had been entered in centimetre, the calculated circumference is in centimetre, as well.)
(The square of the unit the radius had been entered in. If, for example, the radius had been entered in centimetre, the calculated area is in square centimetre.)

## The formula used for the calculation of a circle’s circumference and area from radius:

• The formula used for the calculation of circumference: C = 2 ∙ r ∙ π
• The formula used for the calculation of area: A = r2 ∙ π
❤️ If you've found this useful, share it with others ❤️