Area of a Circle Calculator
A circle’s area is π r² and its circumference is 2 π r. Enter radius or diameter — if you enter diameter, radius is half of that value.
Radius10
Area314.159265
Circumference62.831853
Formula
A = π r². C = 2 π r. r = d ÷ 2.
How to use this calculator
- Choose radius or diameter.
- Enter the length.
- Read area and circumference in square and linear units.
Examples
Radius 10
Area ≈ 314.16. Circumference ≈ 62.83.
FAQ
Which units?+
Use any unit. Area will be that unit squared.
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