It’s been announced by both Bing and Google that they have increased the file size limit of Sitemaps files from 10MB to 50MB.
This means that the uncompressed version musst now be under 50MB, rather than under 10MB.
Fabrice Canel, Principal Program Manager at Bing, said “while most sitemaps are under this 10 MB file limit, these days, our systems occasionally encounter sitemaps exceeding this limit.” He then added, “Most often this is caused when sitemap files list very long URLs or if they have attributes listing long extra URLs (as alternate language URLs, Image URLs, etc), which inflates the size of the sitemap file.”
The 50,000 URL limit per Sitemaps file hasn’t changed, so you will still have only up to 50,000 URLs in a single Sitemap file. But the file size has increased dramatically.
Here’s Google’s tweet about it:
We’ve updated the Sitemaps protocol with Bing! Sitemaps & indexes can be considerably larger now. More at https://t.co/uygpuywUEh
— Google Webmasters (@googlewmc) November 30, 2016