Circle equations formulas and calculator

If you have one unknown variable:

• circumference (c)

• area (A)

• radius  (r)

• or diameter of the circle (d)

just type it in the calculator below. Other values will be calculated quickly using the following formulas:






where π is calculated to 10 significant digits.

Name	Label	Value
Radius	r
Diameter	d
Circumference	c
Area	A

Yabba dabba do :)