Diameter to Circumference
Convert any diameter value to its circumference instantly. Enter the diameter below and get the circumference using the formula C = π × d.
Diameter to Circumference Formula
To find the circumference from a known diameter, multiply the diameter by π (pi):
C = π × d
The circumference C equals pi times the diameter d. Pi (π) is approximately 3.14159265358979.
For example, find the circumference of a circle with a diameter of 10:
C = π × 10 = 31.4159
The circumference of this circle is 31.4159.
Frequently Asked Questions
Multiply the diameter by π (3.14159). The formula is C = π × d. For example, a diameter of 10 gives a circumference of 31.4159.
C = π × 7 = 21.9911. The circumference is approximately 21.99 units.
Because π is defined as the ratio of a circle's circumference to its diameter (C/d = π). Rearranging gives C = π × d. This relationship holds for every circle regardless of size.