Is it really necessary to split your sitemap into multiple files to index a large site?

Why does Google impose a limit of 50,000 URLs per sitemap file?

This technical limit has existed since the inception of the sitemap protocol. Its purpose is to ensure crawling stability and to prevent overly large XML files from overwhelming Google's servers or causing timeouts during parsing.

In practice, a sitemap file can also be limited to 50 MB uncompressed. On sites with long URLs or rich metadata (images, videos), this weight limit may be reached before the URL limit. Therefore, both parameters must be monitored.

How does the structure with sub-sitemaps work?

As soon as a site exceeds the threshold of 50,000 URLs, it is advisable to create a sitemap index file that references several sub-sitemaps. Each sub-sitemap contains a portion of the site's URLs, and the index file serves as a unique entry point for Googlebot.

This architecture is completely standard and used by the majority of mid to large-sized e-commerce sites, media outlets, or SaaS platforms. Google has explicitly recommended it in its official documentation for years.

Is there a risk of negative impact on indexing?

No. Martin Splitt's statement is clear: dividing your sitemap into multiple files is “acceptable”, meaning there is no penalty or technical disadvantage to this approach. Google crawls sub-sitemaps just like a single file.

The only real risk comes from poor structuring: poorly formed index files, orphan sub-sitemaps not declared in the index file, or duplicate URLs between multiple sub-files. These errors can slow down or disrupt crawling.

• 50,000 URLs maximum per individual sitemap file
• 50 MB uncompressed: alternative weight limit to monitor
• Sitemap index file is mandatory once a limit is exceeded
• No negative impact on indexing if the structure is clean
• Errors to avoid: duplicates between sub-sitemaps, orphan files, XML malformations

Is this statement consistent with observed practices on the ground?

Absolutely. For years, large sites have indexed their content using dozens or even hundreds of sub-sitemaps without any issues. Amazon, eBay, Wikipedia: all operate this way. Splitt's confirmation merely reaffirms a norm that is already well established.

However, there are sometimes increased latency in the crawling of certain sub-sitemaps relative to others. This may indicate that Google prioritizes certain files based on their update history or the freshness of the URLs they contain. [To be verified]: no official documentation details precisely how Google allocates its crawl budget among multiple sub-sitemaps of the same site.

What nuances should be added to this 50,000 URL rule?

First point: the 50 MB uncompressed limit can become restrictive before the 50,000 URL limit if your XML entries are rich (image tags, video, multiple hreflangs). In this case, you will need to slice even finer.

Second point: not all CMS or sitemap generators properly manage the automatic creation of sub-files and the index file. Some WordPress plugins, for instance, break the structure once a certain threshold is exceeded, or only update part of the sub-sitemaps. Therefore, it is essential to regularly check the overall consistency.

In which cases is this approach not sufficient?

On sites with very high volume (millions of URLs), splitting your sitemap only addresses part of the issue. The real challenge then becomes the crawl budget: Google will never index all URLs at once, even if they are all declared in clean sitemaps.

In these situations, prioritization is necessary: create sub-sitemaps by content category (premium products, high-value pages, fresh content) and relegate secondary content to separate files. Some SEOs go so far as to submit multiple distinct index files through Search Console to better manage crawling.

What should you do to structure your sitemaps correctly?

First step: audit the volume of URLs on your site. If you exceed 50,000 URLs (or 50 MB), create a sitemap index file (sitemap_index.xml) that points to several sub-sitemaps. Each sub-sitemap must comply with both limits.

Second step: segment intelligently. Don't divide your sitemaps randomly. Group by type of content (products, categories, blog posts, landing pages) or by update frequency. This eases monitoring and allows for quick identification of crawling anomalies in Search Console.

What errors should be avoided when implementing?

Error #1: forgetting to declare the index file in robots.txt. Your Sitemap: line should point to the index file, not to each sub-sitemap individually. Google will discover the sub-files automatically.

Error #2: leaving duplicate URLs between multiple sub-sitemaps. This does not prevent indexing, but Google will crawl the same URL multiple times, unnecessarily consuming crawl budget. Automate generation to avoid such duplicates.

Error #3: not updating sub-sitemaps in real time. If you publish 200 new products daily, ensure that the corresponding sub-sitemap is regenerated and that its <lastmod> date is properly updated. Otherwise, Google may not return to crawl these URLs quickly.

How can I check that my sitemap architecture is working well?

Go to the Search Console, Sitemaps section. Submit your index file, then monitor the number of discovered URLs versus the number of indexed URLs. A significant gap may signal crawling errors or content deemed of low quality by Google.

You can also use tools like Screaming Frog or OnCrawl to crawl your sub-sitemaps and detect inconsistencies: URLs returning 404, redirects, duplicate content. Automate these checks monthly for large sites.

• Create a sitemap index file if the site exceeds 50,000 URLs or 50 MB
• Segment sub-sitemaps by type of content or update frequency
• Only declare the index file in robots.txt
• Check for the absence of URL duplicates between sub-sitemaps
• Automate the regeneration and updating of <lastmod>
• Submit the index file in Search Console and monitor the stats