# Pie Chart

**Pie Chart**- A special chart that uses "pie slices" to show relative sizes of data.

Imagine you just did a survey of your friends to find which kind of movie they liked best.

Here are the results:

Table: Favorite Type of Movie |
||||

Comedy | Action | Romance | Drama | SciFi |
---|---|---|---|---|

4 | 5 | 6 | 1 | 4 |

You could show that by this pie chart:

It is a really good way to show relative sizes: it is easy to see which movie types are most liked, and which are least liked, at a glance.

You can create graphs like that using our Data Graphs (Bar, Line and Pie) page.

Or you can make them yourself ...

## How to Make Them Yourself

First, put your data into a table (like above), then add up all the values to get a total:

Comedy | Action | Romance | Drama | SciFi | TOTAL |
---|---|---|---|---|---|

4 | 5 | 6 | 1 | 4 | 20 |

Next, divide each value by the total and multiply by 100 to get a percent:

Comedy | Action | Romance | Drama | SciFi | TOTAL |
---|---|---|---|---|---|

4 | 5 | 6 | 1 | 4 | 20 |

4/20 = 20% |
5/20 = 25% |
6/20 = 30% |
1/20 = 5% |
4/20 = 20% |
100% |

Now you need to figure out how many degrees for each "pie slice" (correctly called a sector).

A Full Circle has 360 degrees, so we do this calculation:

Comedy | Action | Romance | Drama | SciFi | TOTAL |
---|---|---|---|---|---|

4 | 5 | 6 | 1 | 4 | 20 |

4/20 = 20% |
5/20 = 25% |
6/20 = 30% |
1/20 = 5% |
4/20 = 20% |
100% |

4/20 × 360° = 72° |
5/20 × 360° = 90° |
6/20 × 360° = 108° |
1/20 × 360° = 18° |
4/20 × 360° = 72° |
360° |

Now you are ready to start drawing! Draw a circle. Then use your protractor to measure the degrees of each sector. Here I show the first sector ... ... you can do the rest! |

## More Examples

You can use pie charts to show the relative sizes of many things, such as:

- what type of car people have,
- how many customers a shop has on different days and so on.
- how popular are different breeds of dogs

### Example: Student Grades

Here is how many students got each grade in the recent test:

A |
B |
C |
D |

4 | 12 | 10 | 2 |

And here is the pie chart: