Limitation for google sitemap.xml file size

Question

can any one please let me know the memory limitation(MB) of google sitemap.xml file size.

Answer 1

NOTE : Updated Limits ( as of Sep 10 2016 )

updated limits are

Number of URLs = 50,000 File size ( uncompressed ) = 10MB 

Source : Official Google Guidelines

According to source :

A sitemap file can't contain more than 50,000 URLs and must be no larger than 10 MB uncompressed. If your Sitemap is larger than this, break it into several smaller Sitemaps. These limits help ensure that your web server is not overloaded by serving large files to Google.

For other users, Please ignore the forum links given on other answers,
because those links point to static pages which are not updated.

Answer 2

According to the Latest Update: 01 Jan 2017

Any Sitemap file is limited to 50MB (uncompressed) with a maximum of 50,000 URLs.

And a Sitemap index file (not to be confused with a Sitemap file) can include up to 50,000 Sitemaps.

So, for a single Sitemap index file, the maximum capacity of URLs and storage could be calculated as described below:

in terms of URLs:

50,000 sitemaps = ( 50,000 * 50,000 ) URLs = 2,500,000,000 URLs

Note: Google supports several sitemap formats but still, all formats limit a single sitemap to 10MB (uncompressed) and 50,000 URLs. Please also refer to the sitemap index file's schema as being defined here.

in terms of size:

50MB + (50,000 sitemaps * 50MB) = 2,500,050 MB = > 2.3 TB

So altogether, we can have maximum 2,500 millions URLs by submitting a single site map index file and we can have around 2TB of storage for all sitemap files which are included in the site map index file.

Since we can submit up to 500 sitemap index files to Google see here, the conclusion is:

(500 * 2,500) millions URLs limit with the size of (500 * 2) TB

Reference:

Schema for Sitemap index files

Sitemap formats : Google Webmaster Console

Google supports several sitemap formats such as XML, RSS, mRSS, Atom 1.0 and Text.

All formats limit a single sitemap to 10MB (uncompressed) and 50,000 URLs. If you have a larger file or more URLs, you will have to break your list into multiple sitemaps. You can optionally create a sitemap index file (a file that points to a list of sitemaps) and submit that single index file to Google. You can submit multiple sitemaps and/or sitemap index files to Google.

How big can my Sitemap be? : Sitemaps.org

Sitemaps should be no larger than 50MB (52,428,800 bytes) and can contain a maximum of 50,000 URLs. These limits help to ensure that your web server does not get bogged down serving very large files. This means that if your site contains more than 50,000 URLs or your Sitemap is bigger than 50MB, you must create multiple Sitemap files and use a Sitemap index file. You should use a Sitemap index file even if you have a small site but plan on growing beyond 50,000 URLs or a file size of 50MB. A Sitemap index file can include up to 50,000 Sitemaps and must not exceed 50MB (52,428,800 bytes). You can also use gzip to compress your Sitemaps.