Accessibility Metric

An accessibility metric is a quantitative measure used to assess the level of accessibility compliance of a web page or website. Metrics typically derive from the results of automated or manual evaluation of WCAG checkpoints, aggregating pass/fail/warning outcomes into a single score or rate. Common approaches include the failure rate metric (ratio of failed checkpoints to applicable checkpoints), the WAQM (Web Accessibility Quality Metric), and various weighted scoring systems. A key challenge in accessibility metrics is handling evaluation warnings — items that automated tools cannot definitively classify as pass or fail. Treating warnings as failures (conservative) versus as passes (optimistic) can produce dramatically different accessibility scores for the same page. No single metric fully captures accessibility quality because automated tools can only test a subset of WCAG criteria, and numerical scores cannot represent the qualitative impact of individual barriers on real users.