Ensure users can increase word and letter spacing, line height and paragraph spacing without affecting the readability.
Ensure line height can be increased to at least 1.5 times the font size. [WCAG 1.4.12]
Ensure spacing following paragraphs can be increased to at least 2 times the font size. [WCAG 1.4.12]
Ensure letter spacing can be increased to at least 0.12 times the font size. [WCAG 1.4.12]
Ensure word spacing can be increased to at least 0.16 times the font size. [WCAG 1.4.12]
The preceding practices are all covered by the following WCAG techniques:
Text spacing plays an important role in the readability of digital publications. Text that is densely packed together can be difficult to read and follow not just for those with low vision, but also for those with dyslexia. It also reduces eye strain as users do not have to concentrate as intensely on the screen while reading.
Increased line height, for example, makes it easier for readers to distinguish one line from the next and be able to scan quickly from the end of one line to the beginning of the next.
Increased letter spacing, on the other hand ensure that the letters of a word do no blur together, while increased word spacing improves the ability to distinguish one word from the next.
WCAG's requirements for text spacing establish minimums that users should be able to space text to without losing the content or its functionality (i.e., by using text spacing controls in reading systems). Authors do not have to use these guidelines to prepare their publications, but meeting and exceeding them will improve the default readability. The requirement is only that users be able to increase the spacing without loss of content or functionality.
Text spacing issues are more likely to arise in fixed-layout publications due to the absolute positioning of elements. When spacing is increased, for example, text is more likely to be cut off from view or overlap with other fixed regions.
Reflowable publications are not immune to text spacing issues, but they are rarer. One area where problems can occur is with form controls. If a button is sized to exactly fit the default text styling, for example, increasing the word spacing could cause part of its label to be cut off.