Accessible Power BI reporting

Graphs, charts and tables (visualisations)

We refer to visual presentations of data as visuals or visualisations. Visuals are graphs, charts, tables and matrices.

Choosing the type of visual

Power BI offers many different types of visuals. From simple bar and line charts to more advanced maps and custom visuals.

You should choose the simplest type of visual that presents the information you need.

Simple charts or tables, clearly showing the data, are more effective than complex visuals with novelty features.

More about choosing the right chart on the Government Analysis Function website.

Presenting visuals

Whitespace

Whitespace is the empty space around visuals in a dashboard, or within a visual. The right amount of whitespace in your visuals can help to:

Reduce visual 'noise' and clutter
Highlight the important elements of the visual
Reinforce the important insights or trends in your data

Increase whitespace by:

Using fewer elements
Avoiding unnecessary formatting in your visuals

This will make your visuals more impactful and more comfortable for users to look at.

Sort order

Sort order is the way, or order, that your graph/chart displays the data.

Use a sort order that matches and makes sense with your data. For example:

For time series data, use an oldest to newest sort order
For alphabetical data, use an A-to-Z sort order

For other data series, largest to smallest is usually the best choice.

Sort order is also very important for showing data correctly in the 'Show as a table' option.

Slicers, filters and buttons

Be consistent with positioning and colouring of slicer, filters and buttons across your dashboard. Put them in a logical order.

Gridlines

Gridlines sit in the background of a chart to help users read the data points.

Power BI decides the number of gridlines shown when you add the data. You can choose to show or hide gridlines in many Power BI visuals.

Gridlines can make a visual look cluttered if they are not needed to be able to interpret the data. Consider using data labels instead of gridlines and test this with your audience.

Shapes

Decorative shapes are sometimes used to:

Highlight areas of charts, such as upper and lower confidence limits
Bring attention to specific data points

You must add alternative text to decorative shapes to make them accessible. Learn more about alternative text.

Shapes can be distracting or confusing for people using screen readers or navigating using their keyboard.

Shapes are not linked to the underlying data, so will not update if you can interact with the visual. This may be confusing or misleading.

We recommend using the in-built features within visuals instead of shapes. For example, constant lines and trend lines. Please note: these may not be fully accessible.

Show data graphs as tables

Power BI allows users to view most inbuilt graphs as tables instead. This is helpful if users are unable to see the graph content.

Check that all alternative tables are laid out logically. They should all have understandable column/row titles.

Create your own tables if the visualisation does not provide one or the default version is not suitable. Check the default alternative table by using keyboard command Alt+Shift+F11.

Tooltips

Tooltips are often added to charts to provide extra or supplementary information. You should not use tooltips to convey important or critical information.

Users can hover over the graph to reveal the tooltip.

Tooltips are not accessible by keyboard. This means that they are not accessible for users:

With motor issues
Who do not have a mouse
Who use some screen readers

Types of simple visuals

Bar and column charts

Bar and column charts display data using rectangles. Bar charts use horizontal rectangles (bars). Column charts use vertical rectangles (columns).

Choosing between a bar and column chart will depend on the space and size you have available.

Using a horizontal bar chart is best when there are lots of categories or long category names.

Formatting bar and column charts

Gaps between bars/columns should be narrower than the width of a single bar
Limit stacked bar charts to four categories. Avoid using stacked bar charts where there is a mixture of positive and negative numbers.
Limit clustered bar charts to four bars per cluster. Avoid using clustered bar charts for time series data.

Using colour

If your chart shows a continuous series (time or numbers), use different shades of the same colour for all bars or columns. For example, use the lightest shade for the lowest value and the darkest shade for the highest value.

If your chart shows a categorical series (data with no specific order), use different colours for each bar or column.

Make sure the colours have similar saturation (how pale or bold they are) and tone (how dull or bright they are). This is so that one colour doesn't stand out too much and look like a highlight.

All colours must have an accessible contrast. Learn more about accessible colour contrast.

Line and area charts

Line and area charts display trends over time.

Formatting line and area charts

Limit line charts to a maximum of four lines. Use small multiples if necessary but ensure axes have the same scale. Consider using a focus chart if there are more than 4 lines.
Always use markers when more than one line is being shown. Use different shapes for different lines.
Only use different line styles and weights when meaningful. For example, to show secondary data, incomplete data, forecast, target, subcategory or trend.
Avoid using very thin lines

Tables and matrices

Tables and matrices display data in a structured format. Tables only have row groups. Matrices have row groups and column groups.

Formatting tables and matrices

Align numbers, percentages, currencies, and dates to the right of the column. This makes them easier to read and to compare values down a column. Learn more about formatting numbers.
If using icons, choose icons that are simple and not prone to misinterpretation.
Banded rows can be helpful to some users. They can also be confused with highlighting or colour coding. If using banded rows, make sure there is accessible colour contrast between your text and background on all rows. Learn more about accessible colour contrast.
Conditional formatting can be useful for some users and distracting for others. Ensure that the information the formatting conveys is available in an alternative format. For example, use the Power BI suggested symbols from the conditional formatting menu. A screen reader will read these out.
Limit the number of variables or spread the data across multiple tables or matrices. This will make the data easier to understand.

Complex visuals and accessibility issues

You may need to use more complex visualisations. Be aware that users may not be familiar with them or how to interpret information presented in a new way.

You may need to educate users on new visuals. Learn more about user guidance.

Scatter charts

Scatter charts in Power BI cause problems with screen readers and keyboard navigation. This is because they go to/read out every data point. So, it can be difficult to interpret trends.

Pie charts

Pie charts are not accessible in Power BI. This is because they:

Limit the degree of detail they can convey
Are difficult to compare accurately
Are often misused
Are hard to magnify for better visibility

Maps

Power BI maps are not accessible with screen readers. This includes choropleths, bubble maps and geographic mapping.

How to improve accessibility when using complex visuals

If you use complex visuals, you must:

Ensure that colours meet colour contrast requirements
Ensure that data can be viewed in a table as an alternative
Provide an alternative text description of what the visual shows

Custom visuals

The built-in visuals in Power BI should enable you to show everything you need to.

If you decide to use custom visuals from other developers, you must:

Ensure they are Power BI certified. To identify Power BI certified visuals, sort by 'Power BI Certified'. Power BI certified visuals have a white tick in a blue sun/star shape.
Assess whether they meet the accessibility guidelines in this guidance. Go to the Power BI accessibility checklist.

Text in visuals

When using text in your visuals, follow our guidance on writing text and formatting text.

Titles

Give every visual a descriptive title. Titles should describe what the visual is showing, without being too long. They may also describe the axes.
Use fewer words and 'frontload' titles to ensure important information is read first. For example, "Norfolk population by current age band" not "Breakdown of current ages of people who live in Norfolk".
Use dynamic titles to describe the data. For example "50% of respondents agreed with the proposal". You can create dynamic titles in Data Analysis Expressions (DAX) measures. Learn how to create dynamic titles on the Microsoft Learn website.

Subtitles

Some Power BI visuals allow you to include subtitles. You can use subtitles to give contextual information about the visuals. Such as, what the data is, the geography the data relates to, or the period shown.

Subtitles can also be dynamic. They can change when users interact with the visual or apply slicers or filters. Learn how to create dynamic subtitles via guidance on the LinkedIn website.

Consider whether a subtitle is necessary to avoid adding unnecessary visual elements.

Axes labels

You should use label axes to help users interpret the data. The exception to this is if this information is already shown by the data labels or explained in the title.

All numerical axes should start at 0. This is to avoid misrepresenting differences across your data points.

If your data is condensed into a small range of numbers, use zoom sliders to allow users to change the axes if needed. Zoom sliders only work if there is enough room available in your visual.

If your data's distribution is large, consider using logarithmic axes and spacing out the data points to make them easier to understand.

While many Power BI visuals allow secondary axes, it is best to avoid dual axes, as they can be confusing for users.

Data labels

When you add data labels to a Power BI visual, Power BI decides whether they should sit:

Above or below the lines, or
Inside or outside of the bars or columns

You can change this in the visual settings to ensure the data labels are not difficult to read.

All data label text must have accessible colour contrast with its background. Learn more about accessible colour contrast.

Legends

Limit the use of legends in visuals. They require users to match visual keys such as colour and shape to data items.

If you do need to use a legend, do not rely on colour alone to match the legend to the data. Use different shapes as well.

Items in the legend should appear in a logical order. The legend will be in the same order that data items appear on the chart.

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