# 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:

Comedy Action Romance Drama SciFi Table: Favorite Type of Movie 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:

Comedy Action Romance Drama SciFi Table: Favorite Type of Movie 4 5 6 1 4

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: