Bar chart encodes values as length of rectangles on one baseline. William Playfair, Commercial and Political Atlas, 1786.
In reports, ads and assignments it fits comparing a handful of categories at one time. Skip it when too many categories, 3-D extrusion, or dual-axis tricks.
Principles
- Encoding — Bar chart encodes length of rectangles on one baseline.
- History — William Playfair, Commercial and Political Atlas, 1786
- Fit — comparing a handful of categories at one time
- 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 Bar chart, 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: comparing a handful of categories at one time. 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 length of rectangles on one baseline and decoration falls away.
Bar chart: honour length of rectangles on one baseline, and switch when too many categories, 3-D extrusion, or dual-axis tricks.