Geometry · Technical Drawing
Circle Circumference Calculator
Enter a radius or diameter for a scaled drawing with circumference and area.
Radius (r)
units
Switching between radius and diameter keeps the same circle — the value just gets recalculated for you. Enter any consistent unit (cm, in, m); the drawing scales to fit.
Circumference
0.00
C = 2πr
Radius0.00
Diameter0.00
Area0.00
Full Log
Formulas
C = 2πr · A = πr²
Drawing
To scale
π used
3.14159265