How is accessibility measured using audit scores and usability benchmarks?

Accessibility is measured through a combination of automated audits and manual usability testing. Automated tools like Google Lighthouse, Axe (available as a Chrome extension or integrated into CI pipelines), and WAVE generate accessibility scores and flag specific WCAG 2.1 violations with element-level detail. A Lighthouse accessibility score above 90 is a reasonable baseline target, though it does not guarantee full WCAG compliance.

Manual benchmarking involves structured usability testing with participants who have disabilities, using assistive technologies such as NVDA or JAWS screen readers on Windows, VoiceOver on macOS and iOS, and TalkBack on Android. Task completion rates, error rates, and qualitative feedback from these sessions reveal barriers that automated tools cannot detect, such as confusing reading order, poorly worded labels, or interaction patterns that are technically valid but practically unusable with assistive technology.