Font Accessibility Checker
Check whether a font is likely to be accessible by analysing its x-height ratio, cap-height, weight class, and available bold and italic styles. These are the measurable typographic factors that most affect readability.
What the accessibility checker measures
- x-height ratio (x-height ÷ cap-height): the single strongest predictor of readability at body sizes. Optimal range 0.65–0.78.
- x-height at 16px: if it falls below 7px the font may be hard to read at typical body sizes.
- Cap-height at 16px: larger cap-heights compress vertical rhythm and may need additional line-height.
- Weight class: 400 is standard body weight. Weight class 300 or below at body size reduces legibility.
- Bold and italic availability: whether the font includes these styles or relies on browser-synthesised versions.
Frequently asked questions
What is a good x-height ratio?
0.65 to 0.78 is optimal. Lower ratios look too small at body sizes; higher ratios reduce the distinction between upper and lowercase.
Does this check guarantee accessibility?
No. It measures font-level metrics that affect readability. Final accessibility requires testing rendered text with real users and assistive technologies.
What if my font has no bold variant?
Browsers synthesise bold by thickening strokes, which looks worse than a true bold weight. Use a different font for headings, or choose a family with a full weight range.
Is WCAG 2.2 concerned with font choice?
WCAG 2.2 requires minimum text size, contrast, and spacing but does not prescribe specific fonts. Good x-height, weight, and clear letterforms help meet the readability intent of WCAG guidance.