Circle Calculator
Calculate area, circumference, diameter and radius of any circle instantly with our free online tool. Perfect for students, teachers, and professionals.
cm
m
in
ft
Diameter:
10.00
Circumference:
31.42
Area:
78.54
Circle Visualization
Radius (r)
Circle Formulas
Diameter
d = 2r
Twice the radius
Circumference
C = 2πr
Perimeter of circle
Area
A = πr²
Space enclosed