To calculate your Exchange Server Role Requirements you can now use the latest version of the Exchange Server Role Requirements Calculator >>here<<. It supports you in planning your Exchange Server Deployment based on your requirements.
Further details on how to use the calculator you find in the link in the description of the above linked webpage.
Additionally you can check requirements >>here on TechNet<< or >>Exchange (2013) Deployment Assistant<<.
Supplementary update: In the Technical Summit 2016 in Germany a session included a Exchange Role Requirement Calculation for different versions. You can find this start at around minute 12+ https://channel9.msdn.com/Events/microsoft-techncial-summit/Technical-Summit-2016/Neuigkeiten-von-Exchange-On-Premises-Hybrid-und-Online