What is a Pie Chart?
A pie chart (or circular chart) is divided into slices to illustrate numerical proportion. In a pie chart, the arc length of each slice is proportional to the quantity it represents. It is the default choice for showcasing part-to-whole relationships.
Donut Charts: A Modern Alternative
A donut chart is functionally identical to a pie chart, but has a hollow center. The blank center space can be used to display summary labels or titles, and many cognitive studies suggest donut charts are easier to read because the human brain is better at comparing linear segment lengths than angles.
When should you use a Pie Chart?
- You are showing a **part-to-whole relationship** where the sum of all categories adds up to 100%.
- You have **fewer than 6 categories** to display.
- The categories are **mutually exclusive** (an item cannot belong to two slices).
Pie Chart Common Mistakes to Avoid
- Avoid too many slices: If you have dozens of categories, the slices become too small to compare. Use a bar chart instead.
- Sum must equal 100%: Ensure all combined categories represent the entire dataset population.
- Sort slices logically: Start the largest slice at the 12 o'clock position and progress clockwise to the smallest for easier parsing.