Guide Image SEO · 2 of 6
How to Describe Charts and Infographics With Accessible Text
Describe charts with a clear summary, essential values, and a usable text alternative. Work through one example without inventing causes or hiding the data.
Key takeaways
- State the chart’s purpose before listing details.
- Keep values, units, and limits consistent across formats.
- Use a longer description or table where a short phrase is not enough.
To describe charts well, preserve the facts a reader needs from the visual. Give a clear summary, state the key values and units, and provide more detail where the task needs it. A description should not invent a cause for a trend. This is a focused part of image SEO for search and users, not a replacement for the wider image workflow.
Start with the chart’s purpose
Ask which question the chart answers. A reader may need to compare groups, find a change over time, or choose a next step. Write that purpose in one sentence. The text should support the same task, rather than describe every line and color in the order they appear.
If the visual adds no useful facts, review the choice before writing a long description. The process for choosing a useful blog image can help decide whether a chart, table, or plain paragraph is the best fit. A text version cannot fix a misleading or unnecessary visual.
Separate a short label from the full meaning
Use a short identifier to say what the chart concerns. For a complex visual, place the key detail in nearby text or a linked long description. Keep that route clear. Do not pack a whole report into one dense alt attribute just to avoid adding a useful explanation on the page.
Check whether the nearby page already states some of the meaning. Avoid forcing a screen-reader user through the same long passage twice. Keep the image’s role and the text structure in view. W3C’s complex-image guidance shows a short description combined with a fuller alternative for substantial facts.
Describe charts from their data and labels
Gather the source data, title, series names, units, and date range. Confirm that they match the published visual. A chart may be revised while an old description stays in place. Work from the current source rather than guessing exact values from the height of bars.
Name the main comparison, then add the values needed for the task. Keep totals, rates, and counts distinct. If the chart uses an estimate or a range, preserve that limit in the text. Do not make the alternative sound more exact than the data behind the picture.
Work through one small example
Imagine a fictional chart showing completed setup tasks over three weeks. The values are 12 in week one, 18 in week two, and 15 in week three. These are sample values for this lesson, not a customer result or evidence that any tool improved productivity.
A useful short identifier is “Completed setup tasks by week; values and summary follow.” A longer description can say: “Tasks rose from 12 to 18, then fell to 15. Week two had the highest count. Week three remained three tasks above week one.” This reports the pattern without claiming why it happened.
Provide a table when exact lookup matters
A reader may need the exact values rather than only the trend. In that case, a small table can support the same task. Use clear headers and units. Keep the table close enough that the connection is easy to follow, or provide a descriptive link to the data.
For the example, the table below contains the same three values. A reader can check each week without reading a visual scale. The table does not explain the cause of the change. If the article needs a cause, that claim needs a source or a clearly stated hypothesis.
| Week | Completed tasks |
|---|---|
| 1 | 12 |
| 2 | 18 |
| 3 | 15 |
Keep important words available as text
Check notes, labels, and legends that exist only inside the graphic. A tiny footnote may change the meaning of the whole chart. Include the useful limit in the accessible explanation. Do not omit it just because the visual designer placed it in small type.
Use the images of text review when the problem is a key passage trapped inside an image. That task differs from describing a data pattern. A chart can require both a readable text equivalent for its labels and a clear account of the relationships in its data.
Handle product comparisons with extra care
If the chart compares product features, verify that the labels and values match the actual items being sold. Keep model and variant differences clear. A chart about one model should not silently stand in for an entire product family.
The product-image review covers identity and page context for those visuals. Here, focus on preserving the comparison in text. Do not turn one chart caption into a broad product description or add claims that the graphic’s data cannot support.
Test the alternative against the task
Read the page without relying on the image. Can you answer the question the chart was meant to answer? Check the table, summary, and route to further detail. If a key comparison disappears, add that facts in a form a reader can use.
Ask a second person to compare the visual and the text against the same source values. Check units, direction, time range, and missing cases. This is a content test, not a complete accessibility certification. Record any technical work that the site owner needs to address.
Audit and maintain the published version
When reviewing older pages, include charts in the blog alt-text audit but do not reduce the check to whether an attribute exists. A chart can have nonempty alt text and still hide its key meaning. Assign the fuller description or data table as a separate correction where needed.
DEX can generate visuals as part of an article workflow. A generated chart still needs a checked data source and a matching text explanation. Do not treat a plausible-looking graphic as proof that its numbers are true. Review the output before publishing it under the business’s name.
Keep the visual and text in sync
Assign an owner to the chart’s data and explanation. When the values change, update both versions together. Check the public page after the release, including any linked table or longer description. A correct draft is not proof that the live asset changed.
End with the same question you started with. The reader should be able to get the useful comparison in more than one way. Clear text, checked values, and an honest limit make the chart more useful than a decorative description of its colors alone.
FAQ
Can a short alt attribute hold a whole chart?
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Complex charts often need a short identifier plus a fuller text description or table.
Should I explain why values changed?
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Only when the evidence supports that cause.
Is an accessible chart a ranking guarantee?
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No. It helps people access the information; search outcomes need separate evidence.
Sources
- Complex images · W3C
- Alt decision tree · W3C
Dex SEO is an AI SEO agent for small businesses. Every article here is planned from search data, drafted by Dex, fact-checked against the sources it cites, and reviewed by the team before it is published.
How this article was made: planned and drafted by Dex from search data, fact-checked by Dex (5 claims checked), then approved by the Dex SEO team.