πr²
Circle Area Calculator
A circle's area, circumference and diameter from its radius, diameter or circumference.
Result…
How it's calculated
Area = π × r² Circumference = 2 × π × r r = d ÷ 2 = C ÷ (2π)
Finds a circle's area from whichever measurement you have: the radius, the diameter or the distance round it. Measuring a circumference with a tape and dividing by π is often the easiest way to get the diameter of a post, tank or tree.
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