What Is Index Coverage?

Index coverage is the proportion of a site's URLs that search engines have actually admitted into their indexes — reported in Google Search Console's Pages report and Bing Webmaster Tools. It is upstream of everything in GEO: Google's AI Overviews compose from Google's index, and multiple assistants retrieve via Bing-backed APIs, so an unindexed page cannot be cited no matter how well it is written.

Why coverage breaks at scale

Coverage problems concentrate in programmatic collections — the hundreds or thousands of templated pages GEO strategies often ship. The classic failure statuses tell the story:

• "Discovered — currently not indexed": Google found the URL but declined to crawl it, usually a crawl-budget or perceived-value signal.
• "Crawled — currently not indexed": crawled and judged not worth indexing — the thin-content verdict, and the most common fate of near-duplicate programmatic pages.
• Duplicate/canonical exclusions: faceted URLs and parameter variants consolidated away.
• Accidental noindex or robots.txt blocks: self-inflicted, and responsible for a startling share of "AI never cites us" investigations.

Diagnosing unindexed programmatic pages

1. Export sitemap URLs and diff against Search Console's indexed list; the delta is your coverage gap.
2. Bucket excluded URLs by reason code — remediation differs completely between "discovered" (strengthen internal links, raise crawl priority) and "crawled" (add unique substance per page).
3. Check the Bing side separately via Bing Webmaster Tools, and push updates through IndexNow (live since October 2021) for near-instant discovery in that ecosystem.
4. Raise per-page information gain: unique data, unique examples, unique passages — the same qualities that make pages citable also make them indexable.

Example

A marketplace ships 4,000 programmatic city pages; 90 days later only 1,100 are indexed. Reason codes show 2,300 "crawled, currently not indexed" — the template repeats itself with only the city name changing. Adding per-city inventory counts, local pricing data, and three unique FAQs lifts coverage above 80% in the following quarter, and citations from AI engines follow the index, as they must.

Coverage is a ratio to monitor monthly, not a setup task: index states churn continuously as engines re-evaluate.