Accessibility Score: What It Measures and What a Good Score Looks Like

How is an Accessibility Score Calculated?

Accessibility scores are generated by automated scanning tools that evaluate a page against a defined ruleset, typically WCAG 2.1 Level AA, Section 508, or a proprietary set of rules unique to the tool. The scanner crawls the page’s code and flags elements that violate those rules: missing alt text, insufficient color contrast, unlabeled form fields, missing ARIA attributes, and other common accessibility issues. Next steps depend on the tool; however, most log violations categorize them by type, and assign a severity weight before providing a final score. 

What automated tools can’t detect is only a portion of what accessibility actually requires. Scripted scanners evaluate code — they cannot evaluate experience. Whether a keyboard user can complete a multi-step form without getting trapped, whether a screen reader announces dynamic content changes in a logical order, whether error messages are genuinely understandable to someone with a cognitive disability — these require human judgment. 

More simply, a page can score well on an automated scan and still present real barriers to disabled users. 

This is also why two tools can return different scores for the same page. Each tool makes its own decisions about which rules to include, which WCAG conformance level to follow, how to weight severity, and how to calculate the final number. One tool might penalize a missing skip link more heavily than another. A tool built around WCAG 2.2 will flag issues that a WCAG 2.0-based tool won’t detect at all. The score is always a reflection of that tool’s ruleset, not an objective, universal measure of accessibility.

What is a Good Accessibility Score? 

There is no single score that universally defines an accessible website. As mentioned above, different tools use different scales, different rulesets, and different definitions of what counts as a critical violation. 

That said, practical benchmarks have emerged. A score of 90 or above is widely cited as a passing target. WCAG 2.1 Level AA conformance is the legal and regulatory benchmark that matters most for ADA compliance in the U.S. and EN 301 549 compliance in the EU. For most compliance teams, the operational goal is simple: zero critical violations in whatever tool they’re using to monitor their site. 

The more useful question isn’t what score is “good” in the abstract — it’s what the score tells you about risk. A score of 78 with no critical violations on high-traffic pages is different from a score of 85 with a critical violation on a checkout form. Context determines priority. Scores are a starting point for fixes, not a final verdict on whether or not your site is accessible.