Yes, this is no longer a Mailbox server role calculator; this calculator includes recommendations on sizing Client Access servers too! Originally, marketing wanted to brand it as the Microsoft Exchange Server 2013 Client Access and Mailbox Server Roles Theoretical Capacity Planning Calculator, On-Premises Edition. Wow, that’s a mouthful and reminds me of this branding parody. Thankfully, I vetoed that name (you’re welcome!).
The calculator supports the architectural changes made possible with Exchange 2013
Read on here: http://ow.ly/l1jbg