How to Find the Circumference of a Circle

Finding the Circumference of a Circle

The circumference of a circle is found using the formula:

In the formula, d is the diameter of the circle. The image below shows what we mean by diameter:

How to Find the Circumference of a Circle

Question

What is the circumference of a circle with a diameter of 10 cm, as shown below?

Step-by-Step:

1

Start with the formula:

Circumference = πd

Don't forget: π is pi (≈ 3.14) and πd = π × d.

2

Substitute the diameter into the formula. In our example, d = 10.

Circumference = π × 10 = 31.4 cm

Answer:

The circumference of the circle with a diameter of 10 cm is 31.4 cm.

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See Also

What is the circumference? What is a circle? What is the diameter? What is pi?