### What is a Diameter?

Prior to discussing how to calculate diameter from circumference, let us define a diameter. Diameter is a chord or a straight line segment that runs through the center point of any circle and touches two points on the circumference of a circle. It is the longest possible chord of any circle.

Additionally, a circle’s diameter essentially splits the shape in half.

### What is a Circumference?

Circumference of a circle or perimeter of a circle is the length of the complete arc of a circle. That is, the circumference would be the length of the circle if it were opened up and straightened out to a line segment.

In addition, circumference is represented by the uppercase letter C and it is measured in terms of units of length like centimeters, meters, or kilometers.

### Formula to Calculate Diameter (d) from Circumference (C).

**Example 1:**

Calculate the diameter of a circle whose C is 154 cm.

Hence, the diameter is 49cm.

**Example 2:**

Calculate the diameter of a bicycle wheel if its C is 2155 mm.

**d = C ÷ π**

**= 2155 ÷ 3.142**

**Therefore, the circumference of the wheel is 685.87 mm**

**Example 3:**

Suppose a merry-go-round has a circumference of 78.5 feet. Calculate its diameter.

**d = C ÷ π**

**= 78.5 ÷ 3.142**

**= 24.98 ft**