Divide the circumference value by the number pi (π), or use the formula d = c/π. That's how you find the diameter of a circle with its circumference.

If you want to find the diameter from the circumference of a circle, follow these steps: Divide the circumference by π, or 3.14 for an estimation. And that's it; you have the circle's diameter.

If you know the circumference of the circle, divide it by π to get the diameter. π is equal to approximately 3.14 but you should use your calculator to get the most accurate results.

Where c is the circumference, π is a number and its approximate value is 3.14 and d is its diameter. ⇒ c =π4 = 3.14×4= 12.56 inches ⇒ c =12.56 inches