Treemap encodes values as area of nested rectangles for a hierarchy. Ben Shneiderman, University of Maryland, 1991, for disk-space visualization.
In reports, ads and assignments it fits part-to-whole with many leaves and a hierarchy. Skip it when you need precise comparison of similar sizes.
Principles
- Encoding — Treemap encodes area of nested rectangles for a hierarchy.
- History — Ben Shneiderman, University of Maryland, 1991, for disk-space visualization
- Fit — part-to-whole with many leaves and a hierarchy
- Shared baseline — The eye compares length and position more accurately than area.
- Audience — PowerPoint, Excel or Google Sheets and Meta, Google and retail print share the same geometry.
Misconceptions
- Pretty equals true — Decoration rarely persuades; it slows reading.
- 3-D helps — Perspective distortion wrecks comparison. Keep it flat.
- More series is richer — Do not stack stories. One Treemap, one claim.
- Default palette is fine — Rainbow defaults fail color-blind viewers and grey print. Change Excel or Google Sheets defaults.
Why it matters
- Work — Work: part-to-whole with many leaves and a hierarchy. Readable in four minutes in PowerPoint.
- Ads — Ads: one number and one shape speak first in Meta, Google and retail print.
- School — School: for lab reports and poster boards, pick the form that answers the rubric.
- Craft — Craft: honour area of nested rectangles for a hierarchy and decoration falls away.
Treemap: honour area of nested rectangles for a hierarchy, and switch when you need precise comparison of similar sizes.