# Circumference Formulas

**Circumference of Circle:** Circumference of a circle is defined as the length of outer line of the circle. It is also known as the perimeter of a geometric shape. Circle circumference is the double times radius into π. It is also stated as the enclosing region of any curved geometric figure.

### Circumference Formulas

Circumference of a circle is the linear distance of a circle's edge. Its formulas are provided below:

**1. When you have radius,**

Circle Circumference C = 2πR

Where, R is the radius of the circle

**2. When you have diameter,**

Circumference of Circle C = πd

Area of a circle is nothing but the space occupied by it. its formula is

Area = πR² = (πd²) / 4

Circumference of a Ellipse formulas are

C = π * [3(a + b) - √((3a + b) * (a + 3b))]

C = π * (a + b) * [1 + 3(a - b)²/(a + b)²] / [10 + √(4 - 3(a - b)²/(a + b)²)]

C = π * (a + b) * [1 + 3 * h] / [10 + √(4 - 3 * h)]

### Process to Calculate the Circumference

Here is the simple step by step procedure to calculate the circumference.

- As a first step, collect the radius or diameter of a circle from the question.
- Double the π and multiply it with radius or calculate product of π and diameter to get the circumference.
- Write the circumference of the circle.

### Example Questions on Circle Circumference

**Example 1: Find the circumference and area of circle, if its radius is 25 cm?**

**Solution:**

Given that,

Circle Radius R = 25 cm

Circle Circumference formula is

C = 2πR

Substitute R and π value in the above equation

C = 2 * 3.14 * 25

= 157

Area of Circle formula is

A = πR²

= 3.14 * 25 * 25

= 1,962.5

Diameter of Circle d = 2R

d = 2 * 25 = 50

∴ Circumference of Circle is 157 cm, area is 1962.5 cm² and diameter is 50 cm.

**Example 2: Circle diameter is 3.65 m. Calculate the circumference of circle?**

**Solution:**

Given that,

Diameter of circle d = 3.65 m

Circumference of a Circle formula is

C = πd

Put those values in the above equation

C = 3.14 * 3.65

= 11.461

Circle Area formula is A = (πd²) / 4

= (3.14 * 3.65²) / 4

= (3.14 * 3.65 * 3.65) / 4

= 41.832 / 4

= 10.45

Radius of Circle R = d/2

= 3.65/2

= 1.825

∴ Circumference of circle having diameter 3.65 m is 11.461 m, area is 10.45 m² and radius is 1.825 m.

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### FAQs on Circumference Calculator

**1. How do you get diameter from the circumference?**

Basic circumference of circle formula is 2πr, where r is the radius. We know that double the radius becomes diameter. So, circumference is

C = 2π(d/2) = π * d. Where d is the circle diameter.

**2. What is the circumference of a 15 foot radius circle?**

Given circle radius R = 15 foot

Circumference = 2πR

= 2 * 3.14 * 15

= 94.2

∴ Circumference of a 15 foot radius circle is 94.2 foot.

**3. What is the circumference circle?**

Circumference is the perimeter of a circle. It is the total arc length of a circle. When the boundary of the circle is opened up, it will be straightened out to the line segment.

**4. What is circumference vs diameter?**

Diameter is the straight line that passes through the center of the circle. Circumference is the distance once around the circle. When we divide circumference by the diameter we get 3.14 value. Diameter formula is the double radius. Circumference formula is 2 * π * r.