The Capacity Planning for Skype for Business Server 2015 TechNet documentation has been released as well as the Skype for Business Server 2015 Capacity Calculator. Review the Capacity Planning TechNet documentation here and download the Capacity Calculator here.
Read more at source: http://blogs.technet.com/b/skypecentral/archive/2016/03/29/skype-for-business-capacity-planning-amp-capacity-calculator.aspx