Circle Calculator
Get area, circumference and diameter from the radius of a circle.
π Updated October 13, 2026
About the Circle Calculator
Solve it in seconds with the Circle Calculator. Get area, circumference and diameter from the radius of a circle. Accurate, instant and free β no signup, no app install. Students also reach for the Percentage Calculator and Scientific Calculator.
How to use this calculator
- Enter your numbers in the fields above.
- Results update instantly β no button to press, no page reload.
- Adjust the inputs to compare scenarios with the Circle Calculator.
Keep exploring: Percentage Calculator Β· Basic Calculator Β· Date Difference Calculator Β· Scientific Calculator
Frequently asked questions
What is the area formula?
Ο Γ rΒ².
What is circumference?
2 Γ Ο Γ r.
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