Design Principle
An accessible chart is not a graphic with one alt sentence; its visual encodings, text summary, interaction states, and data alternative all carry the same evidence.
Principle
An accessible chart is not a graphic with one alt sentence; its visual encodings, text summary, interaction states, and data alternative all carry the same evidence.
Design action
Create an encoding ledger for every series, status, and threshold: color is only one channel, backed by direct labels, line styles, symbols, patterns, legends, summaries, long descriptions, table alternatives, and keyboard-reachable tooltips.
Examples
Positive example: Multi-series lines, status distributions, maps, heatmaps, KPI charts, operations dashboards, and public-data charts inform decisions rather than decorate. Counterexample: The chart has only aria-label, red/green lines differ only by color, or key values appear only in hover tooltips.
Apply when
Multi-series lines, status distributions, maps, heatmaps, KPI charts, operations dashboards, and public-data charts inform decisions rather than decorate. Users need to judge state, scope, risk, or next action quickly.
Source notes
Source note: Synthesized from W3C WCAG 2.2, Apple Accessibility, IBM Carbon Accessibility, and accessibility practices in major design systems. WCAG 2.2: https://www.w3.org/TR/WCAG22/ WCAG Contrast Minimum: https://www.w3.org/WAI/WCAG21/Understanding/contrast-minimum.html WCAG Non-text Contrast: https://www.w3.org/WAI/WCAG22/Understanding/non-text-contrast.html Apple HIG Accessibility: https://developer.apple.com/design/human-interface-guidelines/accessibility Carbon Accessibility Overview: https://carbondesignsystem.com/guidelines/accessibility/overview/
Agent Directive
Create an encoding ledger for every series, status, and threshold: color is only one channel, backed by direct labels, line styles, symbols, patterns, legends, summaries, long descriptions, table alternatives, and keyboard-reachable tooltips.