Circle Calculator
Calculate all properties of a circle from any single value: radius, diameter, circumference, or area
Calculation Results
Radius
0
r
Diameter
0
d = 2r
Circumference
0
c = 2πr
Area
0
A = πr²
d = 2 × r
c = 2 × π × r
c = π × d
A = π × r²
About Circles
A circle is a simple closed shape where all points are equidistant from the center point. It’s one of the most fundamental shapes in geometry.
Circle Properties
- Radius (r): Distance from center to edge
- Diameter (d): Straight line through center (d = 2r)
- Circumference (c): Perimeter of the circle (c = 2πr)
- Area (A): Space inside the circle (A = πr²)
π (Pi) is a mathematical constant approximately equal to 3.14159. It represents the ratio of a circle’s circumference to its diameter.