Limitation for google sitemap.xml file size

According to the Latest Update: (as of 2016):

Any Sitemap file is limited to 10MB (uncompressed) with a maximum of 50,000 URLs.
And a Sitemap index file can include up to 10,000 Sitemaps.
So we can have around 50 millions URLs in separated sitemap files.

in terms of URLs:

49,000 URLs + 1,000 sitemaps
= 49,000 URLs + ( 1,000 * 50,000 ) URLs
= 50,049,000 URLs 

in terms of size:

10MB + (1,000 sitemaps * 10MB)
= 10,010 MB
= 10.01 GB 

So altogether, we can have around 10GB of storage for all sitemap files.