can any one please let me know the memory limitation(MB) of google sitemap.xml file size.
The information you're looking for is located at the link below under "Guidelines for Sitemaps". This comes straight from the horse's mouth as they say.
http://www.google.com/support/webmasters/bin/answer.py?answer=183668
I have reached this question while developing for 100K products sitemap.
And limits are
50K URL
50 MB file size limit
To stay safe I think multiple sitemaps will help.
<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<sitemap>
<loc>http://www.example.com/sitemap_1.xml</loc>
<lastmod>2018-01-02T15:11:46+06:00</lastmod>
</sitemap>
<sitemap>
<loc>http://www.example.com/sitemap_2.xml.gz</loc>
<lastmod>2018-01-01T15:11:46+06:00</lastmod>
</sitemap>
</sitemapindex>
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.
UPDATED limits from Nov 30 2016
File size limit has been increased to 50MB per uncompressed file
& URL limits remain 50,000 URLs per sitemap / sitemap index
You can provide multiple Sitemap files, but each Sitemap file that you provide must have no more than 50,000 URLs and must be no larger than 50MB (52,428,800 bytes). If you would like, you may compress your Sitemap files using gzip to reduce your bandwidth requirement; however the sitemap file once uncompressed must be no larger than 50MB. If you want to list more than 50,000 URLs, you must create multiple Sitemap files.
If you do provide multiple Sitemaps, you should then list each Sitemap file in a Sitemap index file. Sitemap index files may not list more than 50,000 Sitemaps and must be no larger than 50MB (52,428,800 bytes) and can be compressed. You can have more than one Sitemap index file. The XML format of a Sitemap index file is very similar to the XML format of a Sitemap file.
Source https://www.sitemaps.org/protocol.html#otherformats
For those who are still confused about the 10MB limit mentioned on the google suppport page, that page is not updated as they announced the changes on Nov 30, 2016.
Announcement by google : https://twitter.com/googlewmc/status/803884180266479616 Announcement by bing : https://blogs.bing.com/webmaster/November-2016/Increasing-the-size-limit-of-Sitemaps-file-to-addr
TL;DR
Limit for Sitemap Files :
50,000 URLs
&50MB uncompressed file size
Limit for Sitemap Index Files :
50,000 Sitemaps
&50MB uncompressed file size
According to a claim in the Wikipedia article, the limit is 50,000 URLs and 10 MB (uncompressed) per sitemap. I think this number is from the Google Webmaster FAQ (can't find the official entry but this Google groups entry says the same.)
Not sure whether this limit applies to the other search engine providers as well.
The answer is clear on the official sitemaps.org:
You can provide multiple Sitemap files, but each Sitemap file that you provide must have no more than 50,000 URLs and must be no larger than 10MB (10,485,760 bytes). If you would like, you may compress your Sitemap files using gzip to reduce your bandwidth requirement; however the sitemap file once uncompressed must be no larger than 10MB. If you want to list more than 50,000 URLs, you must create multiple Sitemap files.
tl;dr sitemaps.xml must be < 10mb when uncompressed, regardless if you're gzipping it or not