Calculate area, circumference, and diameter from any single variable.
Input Dimensions
All properties
10.00units
Radius (calculated)
The complete set of geometric properties for the circle.
Diameter20.0000
Circumference62.8319
Area314.1593
Radius10.0000
r
CIRCLE
About this calculator
Relationships in a Circle
All geometric properties of a circle—radius, diameter, circumference, and area—are interdependent. Knowing just one of them allows you to calculate all the others using the constant π (pi).
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Pro Tips
Radius is the most fundamental measurement.
The diameter is always exactly twice the radius.
Circumference is the distance around the circle.
Area represents the 2D space inside the circle.
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Fun Facts
"The circle is the shape with the maximum area for a given perimeter."
"Pi is roughly 3.14, but its digits proceed forever without repeating."
"The word 'circle' comes from the Greek word 'kirkos', which means 'ring' or 'hoop'."
