The 50,000-URL limit, and when to use a sitemap index

A sitemap file cannot grow forever. The protocol sets two ceilings, and crossing either one makes the file invalid to Google.

The two limits

Each file holds at most 50,000 URLs and 50 MB uncompressed. Whichever comes first wins: a 40,000-page site with long URLs can hit 50 MB before it reaches 50,000 lines. The file may be served gzipped as .gz, but the size limit applies to the uncompressed content.

The sitemap index

When a site crosses either ceiling, the answer is not to drop pages — it is to split them across several files and point to those from an index. The index is itself an XML file with the same limit: up to 50,000 referenced files. In practice that covers 2.5 billion URLs, which no site reaches.

What you register in Google Search Console is the index, not each file. Google follows the pointers on its own.

What GenMap does

The crawl decides this for you. Below the ceiling it emits a single file; above it, GenMap splits the pages and builds the index automatically, honoring both limits at once. You download the set ready to submit.