Darker cells mean a higher score for this topic on that metric.
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Quick answers
When should I pick Bar chart?
When the story is: comparing a handful of categories at one time.
When should I avoid Bar chart?
Skip it in cases like: too many categories, 3-D extrusion, or dual-axis tricks.
Who invented or popularised it?
William Playfair, Commercial and Political Atlas, 1786
What does it encode?
length of rectangles on one baseline
Is it OK in ads?
Yes if one claim is visible at a glance in Meta, Google and retail print; otherwise link to a full figure.
Will a teacher accept it?
Yes for lab reports and poster boards if axes, units and a source line are present.
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.
Rules
- Rules 1 — Use length of rectangles on one baseline as one channel, not two.
- Rules 2 — Direct labels beat a distant legend.
- Rules 3 — Do not hide zero. If you break the axis, say so.
- Rules 4 — Colour encodes category or magnitude, not both.
- Rules 5 — Put the claim in the title, not just "Bar chart".
- Rules 6 — Source and period, even in small type.
Palette
- Palette 1 — Categories: distinct hues. Sequences: one hue, changing value.
- Palette 2 — Diverging: a neutral centre, emphasis at both ends.
- Palette 3 — One brand colour plus greys beats a rainbow.
- Palette 4 — Check contrast on a projector and in greyscale print.
Type
- Type 1 — Tabular figures for numbers. Do not pour body copy into the chart.
- Type 2 — Titles as sentences; axes as short nouns.
- Type 3 — For CJK, drop weight one step and leave tracking.
Bar chart: honour length of rectangles on one baseline, and switch when too many categories, 3-D extrusion, or dual-axis tricks.