Statistics » Pie chart

What is a pie chart?

A pie chart is a schematic representation of data within a circle.

Below you can see an example. The different parts are called sectors.
The sector 'walk' is light blue.
This sector has a sector angle of 20 : 100 × 360° = 72°.

How do you draw a pie chart?

You first have to calculate the size of the angles.
You can calculate the size of the sector angles by using ratio tables or with the formula sector angle = number : total × 360°

Example
A number of pupils is asked what their favorite pet is.
The results are in the table below.

 Cats 74 Dogs 34 Birds 20 Fish 15 Other 7

Draw a pie chart for this data.

First we need to know how many pupils have been asked.
74 + 34 + 20 + 15 + 7 = 150 pupils.

Now we can calculate the sector angles.

With a ratio table:

 number of pupils 150 1 74 34 20 15 7 angle in degrees 360 2.4 177.6 81.6 48 36 16.8

Or with the formula:

 74 : 150 × 360° = 177.6° 34 : 150 × 360° = 81.6° 20 : 150 × 360° = 48° 15 : 150 × 360° = 36° 7 : 150 × 360° = 16.8°

Now you can draw the pie chart. Did you forget how to draw or measure angles? Check angles.