# Pie Chart

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

Imagine you survey your friends to find the kind of movie they like best:

Table: Favorite Type of Movie | ||||

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

4 | 5 | 6 | 1 | 4 |

You can show the data 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:

Table: Favorite Type of Movie | |||||

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 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 |

20% | 25% | 30% | 5% | 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 ...

Finish up by coloring each sector and giving it a label like "**Comedy: 4 (20%)**", etc.

(And dont forget a title!)

## Another Example

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: