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Lighthouse SEO Score: What the Number Measures

Lighthouse is the auditing tool built into Chrome DevTools and behind Google’s PageSpeed Insights. Besides performance, it scores a page in a few other categories. Its SEO category is a set of pass/fail audits on technical search basics, combined into a score from 0 to 100.

What the score covers

The SEO category checks whether search engines can find, crawl and understand the page. The exact list changes between Lighthouse versions, but the core audits are:

• The page can be indexed: no noindex in a meta robots tag or X-Robots-Tag header.
• A successful HTTP status code, not a 4xx or 5xx.
• A <title> and a meta description.
• Crawlable links: links are <a> elements with a real href (see the crawlable links guide).
• Descriptive link text instead of “click here”.
• A valid robots.txt, if one exists.
• Image alt attributes.
• Valid hreflang and a valid canonical link, where present.

Each audit has a weight, and the score is the weighted share of audits that pass. Audits that do not apply to the page (no hreflang, for example) are left out. Some items, such as structured data, are listed as manual checks and are not scored.

What the score does not tell you

A high Lighthouse SEO score means the page has no obvious technical blockers. It says nothing about the quality of the content, how well it answers a search, how many sites link to it, or how fast it loads for real visitors. A page can score 100 and still rank nowhere. A page with a low score, though, usually has a concrete problem worth fixing, and a failing indexability or status-code audit can keep a page out of search entirely.

Treat 90 or more as “no technical basics missing”, not as a ranking forecast.

How to raise it

Open the page in PageSpeed Insights or Chrome DevTools (Lighthouse tab, SEO category) and look at the failed audits. Most fixes are small:

1. Indexing blocked. Remove noindex from pages you want in search. Check both the HTML and the response headers; a plugin or CDN rule can add X-Robots-Tag without you noticing.
2. Missing title or description. Give every template a unique <title> and <meta name="description">. In WordPress, an SEO plugin fills these per post.
3. Uncrawlable links. Replace onclick navigation and href="javascript:void(0)" with real URLs.
4. Link text. Rewrite “read more” and “here” so the text names the destination.
5. Images without alt. Add a short description, or alt="" for purely decorative images.
6. robots.txt errors. Make sure /robots.txt returns plain text, not an HTML page, and that every line uses a known directive.
7. Invalid hreflang or canonical. Use absolute URLs and valid language codes (see the hreflang guide).

Lighthouse tests one page at a time. Run it on each important template (home, category, article, product), not only on the home page.

How PerfoMetrix checks this

We read the SEO category score from the PageSpeed Insights run that the scan already makes. Google loads the page once in a mobile lab browser; we send no extra requests to your site for this check.

If PageSpeed Insights could not measure the page, the check is shown as “couldn’t test” and does not count towards your SEO score. Several of the individual audits (crawlable links, link text) also appear as their own checks in the report.

Further reading: Lighthouse SEO audits and Google Search Essentials.

Last updated October 28, 2026