When to use

At a glance

ComfortableCompact

Darker cells mean a higher score for this topic on that metric.

Clarity62

Persuasion64

Density92

Craft cost50

School fit70

Work fit82

LessMore

Heatmap encodes values as color value of a cell in a row-column grid. Toussaint Loua’s 1873 crime tables; later Toussaint/Bertin and 1990s gene arrays.

In reports, ads and assignments it fits patterns across two categorical axes at once. Skip it when precise lookup of a number, or a rainbow that is not color-blind safe.

Use when

• Use when 1 — Use Heatmap when the story is patterns across two categorical axes at once.
• Use when 2 — Build the first draft in Excel or Google Sheets, then restyle — do not screenshot.
• Use when 3 — In PowerPoint, one Heatmap per slide, claim in the title.
• Use when 4 — For lab reports and poster boards, this form works when the question is comparison or process.
• Use when 5 — In Meta, Google and retail print, keep one number visible at thumbnail size.

Avoid when

• Avoid when 1 — Skip Heatmap in cases like: precise lookup of a number, or a rainbow that is not color-blind safe.
• Avoid when 2 — 3-D, dual axes, rainbow scales
• Avoid when 3 — Undated numbers, undated time series
• Avoid when 4 — Four charts on one slide

Audiences

• Work — PowerPoint
• Ads — Meta, Google and retail print
• School — lab reports and poster boards

Heatmap: honour color value of a cell in a row-column grid, and switch when precise lookup of a number, or a rainbow that is not color-blind safe.

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