Graphs and Charts: How to Write a Long Description

Not all graphs require a long description. More simple graphs and charts can be easily described in 3-4 sentences and can go directly into the Alt-text. When they do need a long description it is important to focus on the facts and data more than any visual elements.

As with maps, ask what is this chart saying? To help answer this question, review the context surrounding the graph.

Are there any striking visual trends in this chart? Remember that charts and graphs are used to give visual impact to data, so summarizing that at the beginning of your description is a good idea.

Begin by providing the title of the graph, and its main purpose (if it is not clear from the title). Then, describe the its structure and design before going into detail, including the type of graph, and the information on the X and Y axes. You want the reader to understand the layout and larger pieces before describing finer details!

If possible, include the data in a table in a long description.

For units, use the full word instead of shortened/abbreviated forms (i.e., Use “seconds” instead of “s”), and ensure units are described consistently throughout the description

See examples on Samples of Alt-Text:Graphs and Charts: Medium Descriptions or Samples of Alt-text: Graphs and Charts Long Descriptions

Remember:

Describe only the visual features that convey meaning. Including implied visual impact.
Focus on the meaning of symbols and not their appearance.
If the chart is about relationships, describe the relationships and not the symbols.
This is something that happens more with flowcharts and family trees, you don’t have to describe all the arrows and lines, instead describe the relationships and take advantage of multiple modalities! Lists, nested lists, and even subheadings can help with these types of charts.

Go to Writing Tip: Using Point Form Technique for a breakdown on how you can start the writing process

Below are the most common chart types we get.

Bar Charts

Below are the guidelines for describing a Bar Chart.

Describe only the visual features that convey meaning.
Focus on the meaning/relationships of symbols and not their appearance.
Describe the layout of the graph before describing specific data (i.e. "A Bar Chart of …")
State what the graph is telling you before you describe its details (i.e. The chart shows murder rates in Chicago from 1990 to 2020.)
Include implied visual impact.
Provide the most relevant information first, like what is being measured on the X and Y axes.
Make sure what you are describing is relevant to the image. Do not simply repeat the titles and labels without providing information about what the graph portrays.
For units, use the full word instead of short forms (ex. Use “seconds” instead of “s”) and ensure the unit is described consistently throughout the description.

For graphs, you can write a summary of the chart and what it is saying then put the data into a table or list for clarity.

See examples on Samples of Alt-Text:Graphs and Charts: Medium Descriptions or Samples of Alt-text: Graphs and Charts Long Descriptions

If you have any questions, post your question on the Alt-Text Q&A

Pie chart

The description for a pie chart needs to reference the following data elements:

The title of the pie chart.
The structure and design of the chart.
The number of variables.
The data point(s) for each variable. This may be a value, a percentage or both.
When describing the data, organize the data into size order to help the user with visualizing and understanding the chart.
Unless colour is integral to understanding the chart, it does not need to be referenced.

See examples on Samples of Alt-Text:Graphs and Charts: Medium Descriptions or Samples of Alt-text: Graphs and Charts Long Descriptions

If you have any questions, post your question on the Alt-Text Q&A

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