Bar chart or pie chart?
Bar charts work best when categories need to be compared. Differences in length are easy to read, and the chart remains useful with several categories. Pie charts suit a small number of positive values that form a meaningful whole when the purpose is to show each item’s share of the total.
Labels and exact values
Use short, clear category names and always state the unit, such as currency, percent, or quantity. Show values on or close to each bar and include a table when useful. Readers can then recognise the pattern quickly and verify the exact figure.
Example
If five purchasing categories have values of 420,000, 245,000, 180,000, 125,000, and 80,000, a bar chart clearly shows the size differences. A pie chart instead shows each category’s share of total spend of 1,050,000.
Common mistakes
Avoid pie charts with many small slices, three-dimensional effects, and truncated axes that exaggerate differences. Sort bars when ranking matters, use consistent colours, and ensure the title, labels, unit, and measurement period make the chart understandable without extra explanation.
Calculate your own scenario
Use the free PurchaseKPI calculator and get the result immediately.
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