How many URLs can a WordPress sitemap hold?

How core splits a large site

The core sitemap is an index that points to one set of files per content type. Each file is a "page" of at most 2,000 entries:

/wp-sitemap.xml                         (the index)
/wp-sitemap-posts-post-1.xml            posts 1 to 2,000
/wp-sitemap-posts-post-2.xml            posts 2,001 to 4,000
/wp-sitemap-posts-page-1.xml            pages
/wp-sitemap-taxonomies-category-1.xml   categories
/wp-sitemap-taxonomies-post_tag-1.xml   tags
/wp-sitemap-users-1.xml                 authors

A site with 9,500 posts therefore has five post files. The index can list up to 50,000 files, so the theoretical ceiling is far beyond any real site.

Why 2,000 when the protocol allows 50,000? Each file is generated by a database query at request time. Smaller pages keep that query and the response fast on modest hosting. Developers can change the number with the wp_sitemaps_max_urls filter, but there is rarely a reason to.

SEO plugins replace the core sitemap with their own and choose their own page size. Hydrogen SEO defaults to 1,000 entries per file, adjustable on its Sitemap screen, as described in XML sitemaps.

The limits that come from the protocol

The sitemaps.org protocol, which Google and Bing follow, sets two limits per file:

• no more than 50,000 URLs;
• no more than 50 MB uncompressed.

A sitemap index has the same 50,000-entry limit for the files it lists. Google's documentation repeats these numbers and adds that you may submit multiple sitemaps and indexes.

In practice only the URL count matters for WordPress. A 2,000-entry file with loc and lastmod is a few hundred kilobytes. Size becomes a consideration only when image or video entries are added to each URL, which is another reason plugin sitemaps use smaller pages.

Does the number of files matter for SEO?

No. Google treats a sitemap as a list of URLs it might crawl, and it does not matter whether 20,000 URLs arrive in one file or twenty. Splitting has two side benefits:

• Diagnosis. In Search Console's Sitemaps report you can open each file and see how many of its URLs were discovered, so a problem with one content type stands out.
• Reliability. Small files are generated quickly and are less likely to time out when a crawler requests them.

What does matter is what is listed. A sitemap should contain only URLs you want indexed: canonical, returning 200, not noindexed. Core's sitemap knows nothing about noindex settings made by a plugin or filter, and it includes authors and tags whether or not you consider them worth indexing. That is the main practical reason to use an SEO plugin's sitemap instead, since it can follow your indexing rules.

Submitting and checking a multi-file sitemap

Submit the index only. Google reads the files listed inside it; adding each page by hand is unnecessary and has to be redone as the site grows.

1. Open the index in a browser and confirm it lists the files you expect.
2. Submit its address under Sitemaps in Search Console. The steps are in submit a sitemap to Google.
3. After processing, click into the index to see per-file status.

Run only one sitemap system. When an SEO plugin provides sitemaps it normally turns the core one off; if both /wp-sitemap.xml and a plugin index respond, remove the extra one from Search Console and make sure robots.txt names a single Sitemap: line.

To verify a file against the protocol, including the 50,000 limit, dates and namespace, paste it into the XML sitemap validator.

Two things remove the core sitemap entirely: ticking Discourage search engines under Settings → Reading, and the wp_sitemaps_enabled filter. If /wp-sitemap.xml returns a 404 on a site with no SEO plugin, check that setting first, then re-save permalinks.