Alt text for charts, graphs and infographics
Complex images hold more information than an alt attribute should. W3C WAI recommends a two-part approach: a short alt that names the image and its main point, and a long description or data table nearby.
Rules for this kind of image
- Alt: chart type + subject + the single most important takeaway.
- Long description: the data, in a table if possible, or a structured paragraph.
- Infographics: provide the full text content as HTML on the page or a linked page.
- Do not rely on colour words alone ("the red line") in the description.
5 examples, weak vs better
Bar chart of yearly sales · Annual report
Weak
chartBetter Bar chart: annual sales grew every year from 2021 to 2025, details in the table below85 charspasses checks
Type, subject, takeaway, pointer.
Line graph of temperature · Climate article
Weak
graph showing temperaturesBetter Line graph of average July temperature in the city since 1950, showing a steady upward trend92 charspasses checks
States the trend the graph exists to show.
Pie chart of budget · Council budget page
Weak
pie chartBetter Pie chart of the council budget: social care is the largest share; full breakdown below87 charspasses checks
Largest slice first; data in text.
Process infographic with 5 steps · Help article
Weak
infographicBetter Infographic: five steps to set up your account, described in the list below75 charspasses checks
The real content is a list; publish it as one.
Organisation chart · About page
Weak
org chartBetter Organisation chart: three departments report to the CEO; structure listed below79 charspasses checks
Hierarchy goes in a nested list.
Have your own images? Draft alt text with the AI alt text generator, then edit it using these patterns.
Questions people ask
How long can alt text for a chart be?
Keep the alt itself short (one sentence). Put the data in a long description: visible text, a data table, a <details> element, or a linked page.
Can AI describe a chart?
Yes. Our image description generator has a chart mode that drafts a short alt and a long description. Check every number against your source data before publishing.