Creating accessible charts can be a challenge. Charts are visual by nature; without careful design, pertinent information may not be communicated clearly to all users. When creating charts, it is important to follow accessibility best practices to ensure your content is understandable and usable for everyone.
While this article provides general principles for creating accessible charts, it does not guarantee that a chart will be fully accessible. In Microsoft Office, charts are highly customizable, and certain design choices may introduce barriers for some users. Additionally, each chart type presents its own accessibility considerations, so charts should be evaluated individually based on their content and context.
Note: In Microsoft Office, charts include what we commonly refer to as charts and graphs. There is no separate graph tool.
Clearly Label All Charts
Fully label all charts to ensure your content is understandable to all users. Include a descriptive title, axis labels, data labels, a legend, and any other relevant labels for your chart. This information is necessary for all users—not just individuals with disabilities.
While screen reader users may not be able to navigate individual data points within a chart (if it has not been flattened), certain identifying information in a chart may still be announced; this includes the chart type (e.g., pie, clustered column, bar, scatter plot) and title.
Note: Chart elements can be edited as long as the chart remains an object. Once the chart is flattened, it becomes an image and can no longer be edited.
Chart 1. Chart elements can be added or edited in the Chart Design tab.
Flatten Charts to Improve Navigation
Charts are largely inaccessible because they exist on a separate drawing layer. As a result, screen reader users may not be able to navigate or read the content within these objects. Because charts are not part of the main document structure, some versions of Microsoft Office may limit how assistive technologies interact with them. For example, some may not allow alternative text to be added. And even when alternative text can be added, it may not be useful if users cannot navigate to the chart itself or access its data.
To improve accessibility, flatten the chart by converting it into an image. This can be done by taking a screenshot of the chart and inserting it back into the document. The new flattened image (e.g., JPEG or PNG) exists within the main content layer, allowing users to navigate to it and access its alternative text.
Alternatively, you can use the Paste Special option in Microsoft Office to convert objects into images without taking a screenshot. This allows you to paste charts as image files rather than floating objects.
Note: On Mac, you can place your cursor where you want to insert the object. Right click and select Paste Special. Choose to insert the object as a JPEG or PNG file.
Resources
Chart 2. If individual chart elements can be selected, the chart is an object on the drawing layer. If not, the chart has been flattened.
Place Charts In Line with Text
Apply In Line with Text Wrapping to all charts. This ensures that all content is read in the correct order for screen reader users. Images not set to In Line with Text may be placed on a separate layer, which can cause them to be skipped or read out of order by screen readers. Keeping charts inline places them within the document’s reading order so that they are encountered at an appropriate time.
Exception: When adding charts in PowerPoint, use pre-set slide layout placeholders. Charts will automatically fit within the placeholder, so alignment adjustments are not needed. All text and additional content should be placed in separate placeholders to maintain accessibility.
Provide a Descriptive Caption
All images should include an image ID and a brief explanation of what the image shows (e.g., Figure 1: Map of Greece or Table 3: Revenue Growth in Quarter 3). Place the caption directly above or below the image within the body of the document so it is accessible to all users. These captions provide context and help assistive technology users determine whether they need to access additional details, such as alternative text.
Provide Alternative Text and Long Descriptions for Complex Charts
Alternative Text
Add alternative text (alt-text) to all charts. Alt-text provides a text description of an image so users relying on screen readers can understand it’s purpose and content, even if they can’t see it! Ensure charts are flattened before adding alternative text so users can navigate to the image and access its description.
Exception: While Excel includes an alternative text field for images, it is not always reliably read by screen readers. To ensure accessibility, include the image description directly in the sheet body—ideally in Cell A1—so it is encountered immediately when the document is opened.
Guidelines for Writing Effective Alternative Text
- Be concise (1 – 2 sentences max).
- Consider the purpose of the image and its target audience. Why is the image used? How much knowledge do you expect the audience to have?
- Avoid redundant statements like “Image of” or “picture of.” A screen reader will already announce that it is an image.
- If the image is already described in the surrounding text, the alt-text can be very short. Don’t duplicate text.
- If an image is purely decorative, mark it as such.
Long Description
For simple charts, alternative text may be enough to fully describe the image. However, many charts are complex, meaning they cannot be fully described in just 1 – 2 sentences. In these cases, a more detailed description of the graph will be needed. This is your long description.
Long descriptions and alternative text do not exist separately from one another; instead, they should be used together. If a chart requires a long description, it should also include alternative text. The alternative text should identify the type of image (e.g., chart, graph) and indicate where the long description can be found.
- Alt Text: “Chart 1.2: Long Description is located in Appendix A."
- Long Description: “Chart 1.2 suggests that…” (in Appendix A)
Resources for Preparing Your Long Description
Chart 3. Complex images need both alternative text and a long description.
Ensure Charts Meet Color Contrast Guidelines
All charts must meet color contrast standards outlined in the WCAG technical guidelines. This includes all chart elements, such as bars, lines, and pie chart segments. Images should have a contrast ratio of at least 4.5:1.
- Normal sized text should have a contrast ratio of at least 4.5:1.
- Large text (18 pt. or 14 pt. bold) should have a contrast ratio of at least 3:1.
- Non-text elements (e.g., chart bars, lines, or shapes) should have a contrast ratio of at least 3:1 against adjacent colors.
- Text in logos do not have a contrast requirement.
Check contrast using tools like the WebAIM Contrast Checker or the Colour Contrast Analyser tool.
Accessibility Tip: Provide spacing between chart elements when possible. This helps ensure contrast is measured against a single background color, rather than multiple adjacent colors.
Bad Example
Chart 4. Chart elements do not meet color contrast standards. The pie wedges are too light against the background.
Good Example
Chart 5. Chart elements do meet color contrast standards. The added spacing between the pie wedges allows contrast to be measured against the background rather than adjacent wedges.
Do Not Rely on Color as the Sole Means of Communicating Information
When using color to convey meaning, it is essential to include a textual or visual alternative so that all users can understand the content. Users who are color blind, have low vision, or rely on screen readers may not perceive color differences and may miss important details. Additionally, screen readers cannot interpret color, so any meaning conveyed through color must also be presented in text.
Bad Example
Chart 6. This chart relies on color alone to convey meaning. The color of each line indicates the year of the data, supported by a color-based legend.
Good Example
Chart 7. This chart does not rely on color alone to convey meaning. The year is indicated by both line color and line style (solid, dotted, and dashed).
Understand the Difference Between Charts and SmartArt
Charts and SmartArt are often confused, but they are not the same.
Charts are built from numbers and datasets, and they are used to analyze or compare information. They are often linked to Excel during the creation process and can be displayed as different chart types, such as bar, line, or pie charts.
SmartArt is built from text and structure, not data. It is used to visually organize information, such as processes (steps), hierarchies, cycles, or relationships. There is no dataset behind SmartArt. Because of this, SmartArt should not be treated as a chart. While it may look similar, it functions as a visual organizer rather than a tool for data analysis.
Note: While many accessibility best practices overlap between charts and SmartArt, they differ in how they are created and used. Each should be evaluated based on its purpose and content.