Capacity Management - Site collection limits

Limit	Maximum value	Limit type	Notes
Web site	250,000 per site collection	Supported	The maximum recommended number of sites and subsites is 250,000 sites. You can create a very large total number of Web sites by nesting subsites. For example, in a shallow hierarchy with 100 sites, each with 1,000 subsites, you would have a total of 100,000 Web sites. Or a deep hierarchy with 100 sites, each with 10 subsite levels would also contain a total of 100,000 Web sites. Note: Deleting or creating a site or subsite can significantly affect a site’s availability. Access to the site and subsites will be limited while the site is being deleted. Attempting to create many subsites at the same time may also fail.
Site collection size	Maximum size of the content database	Supported	A site collection can be as large as the content database size limit for the applicable usage scenario. For more information about the different content database size limits for specific usage scenarios, In general, we strongly recommend limiting the size of site collections to 100 GB for the following reasons: Certain site collection actions, such as site collection backup/restore or the Windows PowerShell cmdlet Move-SPSite, cause large Microsoft SQL Server operations which can affect performance or fail if other site collections are active in the same database. SharePoint site collection backup and restore is only supported for a maximum site collection size of 100 GB. For larger site collections, the entire content database must be backed up. If multiple site collections larger than 100 GB are contained in a single content database, backup and restore operations can take a long time and are at risk of failure.