Circumference to Diameter Calculator
Use this circumference to diameter calculator to quickly convert any circle circumference into its exact diameter. Enter the circumference, choose your unit, and get the diameter, radius, and formula steps instantly.
Convert Circumference to Diameter
Circumference = π × Diameter
Diameter = Circumference ÷ π
Radius = Diameter ÷ 2
What Is Circumference to Diameter?
Circumference to diameter conversion helps you find the straight-line width of a circle when you already know the distance around the circle. This is useful in geometry, engineering, construction, pipe measurement, wheel sizing, fabric cutting, circular design work, and many practical measurement tasks.
Accurate Formula
The calculator uses the standard circle formula: diameter equals circumference divided by pi.
Multiple Units
Calculate in millimeters, centimeters, meters, inches, feet, or yards without changing the formula.
Instant Answer
Get diameter, radius, and the calculation step immediately for fast and reliable circle measurements.
How It Works
This circumference to diameter tool follows the same mathematical rule used in geometry. Since every circle has a fixed relationship between circumference and diameter, the answer is calculated by dividing the circumference by π.
Enter the Circumference
Type the known circumference value into the input box. For example, enter 31.416 if the circle distance around is 31.416 cm.
Select the Measurement Unit
Choose the unit you are working with, such as centimeters, inches, feet, or meters.
Calculate the Diameter
The tool divides the circumference by π and displays the diameter with the same unit.
Use the Radius Result
The radius is also shown by dividing the diameter by 2, which is helpful for design and measurement work.
Common Formula Example
If a circle has a circumference of 31.416 cm, then:
Diameter = 31.416 ÷ 3.14159
Diameter = 10 cm
Radius = 10 ÷ 2 = 5 cm
FAQs
How do you convert circumference to diameter?
To convert circumference to diameter, divide the circumference by π. The formula is: Diameter = Circumference ÷ π.
What is the diameter if circumference is 100?
If circumference is 100, the diameter is 100 ÷ 3.14159 = 31.83 approximately.
Does the unit change during conversion?
No. If the circumference is entered in centimeters, the diameter will also be in centimeters. The same applies to inches, feet, meters, and other units.
What is the difference between diameter and radius?
The diameter is the full straight distance across the circle through the center. The radius is half of the diameter.
Is this calculator useful for pipe and wheel measurements?
Yes. If you know the outside circumference of a pipe, wheel, ring, or circular object, this calculator can estimate its diameter quickly.