Let’s Calculate Circumference

Circumference Calculator

circle calc: find c — Our circumference calculator, requires any one value to be entered and its displays other remaining values.

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Remember, the input can only be in feet (ft), inches (in), yards (yd), centimetres (cm), millimetres (mm) and metres (m) but never a combination of two different units!

Circumference of a Circle = π x d
π = 3.142 (Constant value)
d = Diameter (drop down ft, in, yd, cm, mm, m)

How to find out circumference of the circle? circle calc: find c

c refers to the circumference of a circle – that is, the circular length of the line that you draw around a circle with compass.
You can calculate it in the following ways:

If you know the radius or diameter of the circle:
Formula to find circumference : c = 2πr = πd

If radius and diameter is unknown, then
Formula: c = 2√(πa)

Understanding the Circumference Calculator:

To understand how to calculate circumference we must first begin with the definition of circumference. Circumference of a circle is linear distance around outer border of a circle. To find out the circumference, we need to know its diameter which is the length of its widest part. The diameter should be measured in feet (ft) for square footage calculations and if needed, converted to inches (in), yards (yd), centimetres (cm), millimetres (mm) and metres (m).

The formula:
Circumference of a Circle = π x d
π = 3.142
d = Diameter (drop down ft, in, yd, cm, mm, m)
Abbreviations of unit area: ft2, in2, yd2, cm2, mm2, m2

Use of calculators:

The calculators of mathematics are very interactive and exclusive. These calculators are ideal used to verify the work, or to solve complex & tricky problems. These calculators are a problem-solving instrument, and should not replace with any old math tricks. Geometry is the branch of mathematics that comprises of the parts of a circle like:

  • Radius
  • Diameter
  • Pi
  • Circumference of Circles
  • Area of Circles

Significance of circle:

Circle itself by its definition is a simple & closed shape. It is a set of all points in a plane that are of the same distant from a given point, called as the center. It can also be known as a curve, outlined by a point where the distance from a given point remains same as the point changes. While a circle, symbolically, signifies various things to different people that include the concepts like infinity, persistence, and entirety.

What defines the Circumference of a circle?

Circumference of a circle is the linear distance that is measured along its sides. It is parallel to perimeter of a geometric figure, but the term ‘perimeter’ is rather used to describe the property of polygons. Circumference is often wrongly spelled as circumfrence.

The distance around the outside of the circle is known as circumference of a circle. It is considered as the perimeter of other shapes like squares. Thus, the shapes that are comprise of straight lines, the word perimeter is used and for circle the word circumference is used. The circumference of a circle can be known as the distance around the circle, or the length of a path along the circle.

Not just this but there are some significant distances on a circle that needs to be calculated before finding the circumference of the circle. And they are radius (r) and diameter (d). Diameter is the distance from one side of the circle to the other, crossing through the center/ middle of the circle. The radius is half of the diameter.

All of these values are linked with the mathematical constant π, or pi, which is the proportion of a circle’s circumference to its diameter, and is nearly 3.14159. Pi or π is an irrational number, means that it cannot be stated accurately as a fraction (though it is often estimated as 22/7). The decimal representation of π never ends or has a perpetual repeating pattern. It is also a moving number, means that it is not the base of any non-zero, polynomial that has rational coefficients.

Aspects of the circumference of a circle:

Circumference calculator performs in many aspects like:

  • Circumference to diameter calculator
  • Circumference to radius
  • Circumference to area
  • Radius to circumference
  • Radius to diameter
  • Radius to area
  • Diameter to circumference
  • Diameter to radius
  • Diameter to area
  • Area to circumference
  • Area to diameter
  • Area to radius

If you are familiar with the diameter or radius of a circle, then you can easily solve out the circumference. To start with, keep in mind that Pi is a number, represented as the symbol π. Pi or π is nearly equal to 3.14. Therefore, the formula for finding out the circumference of the circle is Circumference of circle = π x Diameter of circle, which we typically write in the short form as C = πd. This shows us that the circumference of the circle is three “and a little” times as long as the diameter.

You can also find out the circumference if you know the radius. Keep in mind that the diameter is double the length of the radius. This means whatever is the radius, it should be multiplied with 2 in order to find diameter. It is understood that C = πd. And we know that if r is the radius of the circle, then d = 2r. Hence, C = 2πr.

Finding the out circumference of the Earth:

Using the above calculations, it’s easy to solve the circumference of the Earth! Scientists have founded the diameter of the Earth to be 12,742km. Provided this information, what is the circumference of the Earth?

We all know that C = πd, and here the diameter i.e. d = 12,742km. So, we can quickly find out the circumference of the Earth as C = π x 12,742km = 40,030km.


  • A real-life and original example of a radius is the spindle of a bicycle wheel.
  • A 9-inch pizza is an example of a diameter: when a person makes the first cut to slice a round pizza pie in half, this cut is the diameter of the pizza. So a 9-inch pizza has a 9-inch diameter.

Question 1:

A circle has a diameter of 10cm, what is its circumference?

Answer 1:

Though we know that C = πd. As the diameter is 10cm, we have that C = π x 10cm = 31.42cm.

Question 2:

A circle has a radius of 3m, what is its circumference?

Answer 2:

We know that C = 2πr. As the radius is 3m, we have that C = π x 6m = C= 18.84.

Circumference to diameter:

It has been observed that since diameter is twice the radius, the proportion between circumference and diameter is equal to π i.e.

Formula to calculate diameter using circumference:

C/D = 2πR / 2R = π

This proportion of circumference to diameter is the description of the constant pi. It is used in different areas, such as physics and mathematics.


The number is the proportion of the circumference of a circle to its diameter. The value of is around 3.14159265358979323846…

The diameter of a circle is twice to that of the radius. If the diameter or radius of a circle is given, then we can easily find the circumference. We can also find the diameter and radius of a circle if the circumference is given. We round off to 3.14 in order to simplify our calculations. Circumference, diameter and radii are calculated in linear units, such as inches and centimeters. A circle has many different radii and many different diameters, and each one passes through the center.

Conversion factors:

To convert among square feet, square inches, square yards, square centimetres, square millimetres and square meters you can utilize the following conversion table.

Square feet to square yards multiply ft2 by 0.11111 to get yd2
Square feet to square meters multiply ft2 by 0.092903 to get m2
Square yards to square feet multiply yd2 by 9 to get ft2
Square yards to square meters multiply yd2 by 0.836127 to get m2
Square meters to square feet multiply m2 by 10.7639 to get ft2
Square meters to square yards multiply m2 by 1.19599 to get yd2
Square meters to square millimetres multiply the m2 value by 1000000 to get mm2
Square meters to square centimetres multiply the m2 value by 10 000 to get cm2
Square centimetres to square metres multiply the cm2 value by 0.0001 to get mm2
Square centimetres to square millimetres multiply the cm2 value by 100 to get mm2
Square millimetres to square centimetres multiply the mm2 value by 0.000001 to get cm2
Square millimetres to square metres multiply the mm2 value by 1000000 to get m2