It’s best practice to use tables for presenting data, not for formatting text on a page. Tables used for layout purposes, rather than to structure data, can be confusing for assistive technology users. When creating tables, you should avoid merged or split cells whenever possible. Instead, tables should have a simple, consistent structure (the same number of columns and rows) throughout. This helps avoid confusion for assistive technology users and people with cognitive and learning disabilities. Furthermore, tables must have header rows and columns correctly designated (under Table Design) so that assistive technology will interact correctly with them. Don’t put your table title in the first row of your table – put it just before your table. And finally, choose a visual style for your table that meets minimum color contrast and will be easy to parse for readers with visual processing disorders and cognitive and learning disabilities.
Use tables for data, not text layout
Tables are intended to contain tabular data. That is, a table should have headers: a horizontal row header, a vertical row header, and sometimes both. Inside the table cells there should be numbers or short text items that relate directly to the header or headers at the top of the column or at the beginning of the row.
Tables are not intended to structure the layout of a document when there is no tabular relationship between the headers and cells. Using a table simply because it provides a pleasing visual layout in your document is not the best approach and can create confusion for assistive technology users.
A better way to structure a slide with complex layout is to create a new master slide and position content placeholders within that master slide to match your desired layout.
Avoid merged cells and split cells
It is technically possible to create merged cells and split cells in a table in PowerPoint, but they can create significant barriers for assistive technology users. Both of these structures result in irregular tables which are problematic for screen reader users in particular. Furthermore, they can create difficult to solve problems with table regularity if the document is later converted to PDF.
Use correct header designations
When a screen reader user encounters a table in a slideshow, they will likely use special key commands to navigate that table. These key commands allow the user to hear the data in each cell, as well as any associated information in the column and/or row headers. This means that a screen reader user can read the table with the same ease as a sighted user without having to continually navigate from the cell data back to the header data. In order for this feature to work, headers need to be correctly designated.
When your table is selected, a menu option for “Table Design” will appear in the ribbon. Go to Table Design, then Table Styles. Usually the options for both “Header row” and “First column” will be selected by default. “Header row” refers to what are more commonly called column headers; “First column” refers to what are more commonly called row headers. A column header appears at the very top of a table column and provides information about all the cells that are ranged under it. A row header appears at the far left of a row and provides information about all the cells that come to the right of it. Some tables have both row and column headers; some have only one or the other; and some tables have no headers. Select or deselect the options for “Header row” and “First column” to correctly reflect the structure of your table. (Key commands: Alt, JT, O or M)
Note that when you select or deselect these options it may change the visual appearance of the headers in your table. You can readjust the appearance of your headers by going to Font under the Home tab (Key commands: Alt, H, FF)
If your table has a title, don’t put the title inside a cell or a series of merged cells. Make your title a Heading that comes just before the table.
Visual table styles
You may want to alter the style of your table. You can do this by selecting the table and going to Table Design and then Table Styles (Alt, JT, A). In most instances, a grid table is a more accessible choice than a list table, because grid tables have clear borders around all data cells. You may have to fully open the Table Styles dialog box to view this distinction.
An accessible table also must have sufficient contrast between the text color and the background color. Using zebra stripes (alternating dark and light rows) in your table design can help some readers parse the table more easily without losing their place. However, be sure that the shaded cells meet color contrast minimums: 4.5 to 1 color contrast for regular size text (defined as less than 18-point normal weight, or 14-point bold). Note that some of the built-in PowerPoint table styles with zebra stripes lack sufficient color contrast. Therefore, you should always be prepared to test your table with a reliable color contrast tool.
Relevant Standards