Strength of Evidence:
Document Type: Guideline
Page Structure - General
If reading speed is most important, use longer line lengths (75-100 characters per line). If acceptance of the Web site is most important, use shorter line lengths (fifty characters per line).
When designing, first determine if performance or preference is most important. Users read faster when line lengths are long. However, they tend to prefer shorter line lengths, even though reading shorter lines generally slows overall reading speed. One study found that line lengths of about twenty characters reliably slowed reading speed.
When space for text display is limited, display a few longer lines of text rather than many shorter lines of text. Always display continuous text in columns containing at least fifty characters per line.
Research done using a paper-based document found that medium line length was read fastest.
Related Usability Guidelines: