Capacity Limits for SharePoint Server 2013 and SharePoint 2013 Online
When working within SharePoint 2013, it is critical to respect the software boundaries, thresholds, and limits of the platform. Please note that SharePoint Online is more generalized and focused towards storage.
SharePoint Server 2013 Software Boundaries and Limitations:
http://technet.microsoft.com/en-us/library/cc262787.aspx
SharePoint 2013 Online Software Boundaries and Limitations
http://office.microsoft.com/en-us/office365-sharepoint-online-enterprise-help/sharepoint-online-software-boundaries-and-limits-HA102694293.aspx