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Circumference Calculator
Circumference Formula: If Area is used = sqrt(Measurement/3.14159265)*(2*3.14159265)
If Diameter is used = Measurement*3.14159265

Circumference Definition
The circumference is a distance measurement that shows the length of the line that creates the outside of the circle. One simple way to find the circumference is to use a string and wrap it around a round object. The point where the string overlaps itself should be marked. When you straighten out the string, measure between the marked point and the end of the string to find the circumference.

Why You Need To Know the Circumference
Knowing this distance around a circle can be very useful in many situations. These include:
  • Basic math problems
  • Calculating building materials for a round space
  • Finding the distance around a circular pond or water garden
  • Finding how far a wheel moves with each turn
  • Calculating the distance around a circular track or path
Information Needed for This Calculator
To use this calculator, you will need one of two measurements about the circle in question. These are:
  • Area: This is the measurement of the area of the inside of the circle in square units.
  • Diameter: This is the greatest distance between two points on the circle.

The units used for measuring either the area or the diameter will be the same as the circumference. For instance, if you input 2 inches for the diameter, the circumference will be in inches, or if you use 3 centimeters squared for the area, the circumference measurement will be in centimeters.

Formulas for Circumference
Since you put one of two pieces of information into the circumference calculator, there are two ways to calculate circumference. If you use the diameter of a circle, the calculator uses the formula that multiplies diameter by the number pi, which equals approximately 3.14. If you use the area, the calculator divides the area by pi and takes the square root of that answer to find the circle’s radius, which is half the diameter. Doubling this number and multiplying it by pi is how the circle’s circumference is found.
Check out some of our the other math calculators on the site

How to Calculate Circumference
Let's be honest - sometimes the best circumference calculator is the one that is easy to use and doesn't require us to even know what the circumference formula is in the first place! But if you want to know the exact formula for calculating circumference then please check out the "Formula" box above.