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# Circumference of a circle
- URL: https://www.esheets.io/circumference-of-a-circle/
- Published: 2025-02-02T20:39:14.000Z
- Updated: 2026-06-21T16:41:51.000Z
- Author: Richard Linnington
- Tags: Maths, Geometry and Shape

The circumference of a circle is the distance around its edge, much like the perimeter of a shape. You can think of it as the length of a circular path—like the track of a racecourse or the rim of a bicycle wheel. [Jump to the questions](#practise-now)

## Practise now

Worksheet preview and key skills 

### Worksheet preview

Practise circumference of a circle with this self-marking maths worksheet.

The interactive worksheet below generates questions, gives instant feedback, and lets students record their score.

#### What you’ll practise

- Identifying the radius or diameter.
- Using C = πd or C = 2πr.
- Multiplying by π.
- Giving the answer with suitable length units.

Use the interactive worksheet below, or read the [Topic guide](#topic-guide) for the method and worked example.

Calculate the circumference using the pi button on your calculator or alternatively use 3.142\. Round to 1 decimal place.

  
## Topic guide

### What this worksheet practises

This worksheet provides practice on calculating the numerical circumference of a circle. The circumference is the distance all the way around the outside edge of the circle (its perimeter).

### Key method

The formula to find the circumference is C = πd.

- Determine the diameter ('d'). If the question gives you the radius instead, you must double it first.
- Multiply the diameter by π using the π button on your calculator. If you don't have a scientific calculator, use 3.14 as an approximation.
- Round your final answer to the required degree of accuracy (usually 1 or 2 decimal places).

### Worked example

**Calculate the circumference of a circle with a diameter of 12 cm. Give your answer to 1 decimal place.**

Step 1: Identify the diameter. Here, d = 12 cm.

Step 2: Use the formula C = πd.

C = π × 12

C = 37.69911...

Step 3: Round the answer to 1 decimal place. The second decimal digit is 9, so we round up.

C = 37.7 cm.

### Common mistakes to avoid

A frequent error is using the radius instead of the diameter in the calculation. Always pause and ask yourself: "Do I have the line halfway across, or the line all the way across?" Another common pitfall is rounding too early in the calculation, which can distort your final answer.

### How to check your answer

Since π is approximately 3, the circumference will always be roughly three times the diameter. If the diameter is 12, the answer should be a little more than 36\. If your calculator shows something wildly different, you likely pushed the wrong button.