A pie chart is a circular graph that presents values as proportionate slices.
Pie charts are one of the most commonly used data visualizations but are often not the most effective way to compare data values. This is mainly due to the size of each slice and the number of data categories being represented. Pie charts can also be represented as a doughnut chart, which is generally better for users to compare the size of each slice or arc.
2018 Annual Sales
Always consider using a bar chart or displaying values directly before using a pie chart.
Always include a legend or label slices directly.
Always ensure that the values of the slices total to 100%.
Never use three dimensional (3D) graphics as they distort the visual calculation of volume.
If you are not presenting the proportion of a total, it is recommended to use a bar chart.
If differences between the sizes of slices are subtle, it is recommended to use a bar chart.
It is not recommended to include large gaps between each slice, such as in an exploded pie chart.
It is not recommended to use multi-level pie charts as they are difficult to decipher.