Circumference to Diameter Calculator

Created by Luis Hoyos
Reviewed by Wojciech Sas, PhD
Last updated: Mar 27, 2023

The circumference to diameter calculator can help you solve the geometry problem of finding the circumference of a circle by inputting its diameter. This calculator works both ways, so you can also convert a diameter to a circumference.

Keep reading to learn more about:

  • The circumference to diameter formula.
  • How to calculate circumference from the diameter.
  • How to get diameter from the circumference.

The circumference to diameter formula

Diameter and circumference are lengths related to each other — the higher the diameter, the higher the circumference. The circumference to diameter formula connects these variables in a single equation:

c = πd,


  • c stands for the circumference;
  • d for the diameter; and
  • π is the pi number.

If on the other side, you're interested in how to calculate diameter from the circumference, you can solve for d in the above equation:

d = c/π.

💡 Did you know?
As you can imagine from the above equations, the number π is a constant equal to the circumference-to-diameter ratio of a circle (π=c/d). If you divide the circumference by the diameter, independently of the size, it'll always be 3.14159265...

How to find circumference from diameter: an example

Let's look at an example. Suppose you want to find the circumference of a 5 cm diameter circle. These would be the steps to follow:

  1. Use the appropriate equation, which, in this case, is the circumference to diameter formula: c = πd.
  2. Input the diameter in the equation: c = π × (5 cm) = 15.708 cm.
  3. That's it. Also, check your results using our circumference to diameter calculator. Input 5 cm in the diameter box. Your result should also be 15.708 cm.


What is the circumference of a 6-foot diameter circle?

18.8496 feet. To convert diameter to circumference:

  1. Take the diameter.
  2. Multiply it by the number pi (π).
  3. In this case, the circumference equals: π × 6 ft = 18.8496 ft.

How do I get diameter from circumference?

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

Luis Hoyos
Image of a circle with radius, diameter, circumference and area marked.
Diameter (d)
Circumference (c)
Check out 23 similar 2d geometry calculators 📏
AreaArea of a rectangleArea of crescent… 20 more
People also viewed…

Acute triangle

The acute triangle calculator helps you decide if a given triangle belongs or not to the class of acute triangles.

Geometric mean

Calculate the geometric mean of up to 30 values with this geometric mean calculator.

Test grade

With this test grade calculator, you'll quickly determine the test percentage score and grade.


Use our titration calculator to determine the molarity of your solution.
Copyright by Omni Calculator sp. z o.o.
Privacy policy & cookies
main background