Minergate does have an inbuilt tool that calculates this for you, just running on CPU is around $25 a year, using a graphics card you can usually do around $1-2 a day, minergate however isn't the most profitable as they have been accused of market rigging and points shaving. Personally once you feel comfortable I would just mine XMR directly as this is the most profitable at the moment and has been for a good few months now.