A sector graph is also called a pie chart, and has the following characteristics:

- a circle is divided into sectors
- the angle at the centre of each sector is in proportion to the value of the data it represents
- the value of the data is each sector is found by measuring the angle of the sector at the centre, divided by the 360° and then multiplying the total number of the data in the sector
- in other words, value of the sector =
- no axes are needed for this graph

Sector graphs work best when you have to represent information or data that is expressed as a fraction or percentage of a whole.