Character-related factors
Stroke width
Stroke width is determined by the width of the stem of a character. It may be referred to as light or bold, for example, though these terms are not used consistently across all fonts. In body text, stroke width should be neither too fine, to ensure adequate contrast with the background, nor too bold, to avoid making the counters and apertures in the letters too small.
As a general rule, suitable stem widths for body text range from 10% to 20% of x-height, while those for consultation text range from 13% to 20% of x-height.1
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Recommended stem widths are 17% to 20% of x-height for signage texts with a minimum of 12% of x-height for hairline strokes. This applies to sans serif typefaces with low stroke-width contrast in normal and regular font weights2 . These recommendations also apply to reading and consultation texts intended for readers with visual impairments.
Summarized Recommendations
Stroke width
- Use regular fonts (also referred to as normal, book, Roman and text fonts)
- Avoid very fine and very bold typefaces
- Avoid typefaces with high stroke-width contrast