Why a 100 Google Lighthouse Score Does Not Mean Your Website Is Accessible

A 100 Lighthouse score does not equal WCAG compliance because Lighthouse only runs the automated checks it is able to run, and many WCAG requirements can only be judged by a person. Lighthouse is a good first filter. It is not an audit.

What Lighthouse does well

Lighthouse reliably catches issues a machine can detect from the page code:

• Images with no alt attribute
• Text with low color contrast
• Form fields with no label
• Buttons and links with no accessible name

The same is true of axe DevTools and WAVE. They are valuable, and you should run them. Fixing what they report is a sensible place to start, and our guide to fixing common accessibility issues walks through the usual fixes.

Where a 100 score hides real barriers

Automated tools can confirm that something exists. They often cannot confirm that it works for the person using it. These are patterns manual auditors find on pages that already score 100:

• Alt text that is present but useless. A file name or the word “image” passes the check but tells a screen reader user nothing.
• Modals that do not manage focus. A dialog opens, but keyboard focus stays behind it, or it cannot be closed with the Escape key.
• Illogical focus order. Every control is reachable, but tabbing jumps around the page in an order that makes no sense.
• Silent updates. Content changes after a user action, such as a cart total or a validation message, and a screen reader never announces it.
• Forms that fail users. Fields have labels, but errors are not tied to the right field or do not explain how to fix the problem.

None of these trigger a failed Lighthouse rule, yet each can stop someone from finishing a task.

What a manual check involves

A practical manual pass takes four steps:

1. Put the mouse aside and complete the main user journey using only the keyboard.
2. Repeat the journey with a screen reader and listen for missing or confusing announcements.
3. Check that every dynamic change, such as menus, dialogs, alerts and loading states, is exposed to assistive technology.
4. Review the result against the WCAG 2.2 success criteria. WCAG 2.2 is the current W3C Recommendation.

How to build a stronger process

Use automated scans for fast, repeatable coverage, and use manual expert review for judgment. Wally, the accessibility audit platform, combines both: automated scans run across your site, and manual audits by certified experts are included. Developer remediation support is available as an add-on when your team needs help fixing what the audit finds. You can see how the platform works, read about our audit services, or try the free accessibility tools to start.

A high Lighthouse score is a good sign. Treat it as the start of your accessibility testing, not the finish.