Treemap vs pie chart
Both show parts of a whole. The difference shows up at the tail: a pie turns a small category into an unlabellable sliver, while a treemap gives it a rectangle you can still write in. If your data spans an order of magnitude, that is the whole decision.
Both charts below are the same data — Cloud costs — so the difference you see is the chart type, not the numbers.
Pie chart
Use it when
- Three or four categories of broadly similar size.
- The reader should think in halves and quarters.
- The chart is small and needs to read at a glance.
- The whole is a familiar quantity, like 100%.
Treemap
Use it when
- Five or more categories, or a wide spread between largest and smallest.
- Labels and values need to sit inside the shapes.
- The chart fills a rectangular slot on a dashboard.
- You want the biggest contributor to be visually unavoidable.
Which one
Under five similar categories, use a pie. Beyond that, or whenever the biggest is more than about ten times the smallest, use a treemap — it keeps the small ones legible, which is precisely what a pie cannot do.
Questions people ask
- Can people compare areas accurately?
- Not precisely — area is a weaker visual encoding than length. Treemaps are for showing relative magnitude and structure, not for reading exact values, which is why the numbers belong inside the tiles.
- When should I use a bar chart instead of either?
- Whenever precise comparison matters more than the sense of a whole. Bars are read by length against a shared baseline, which is the most accurate encoding available.