It's basically a 5-in-1 calculator for electric powered model airplanes, helicopters, multicopters, cars, trucks and buggy's, if fact anything that uses rechargeable* batteries. (*As long as the voltage is known then any rechargeable battery including LiPo, LiFe, NiCd and NiMh batteries can be used for some calculations). If you know the current draw of your system additional calculations can be made. In the calculator all the calculations are made "on-the-fly" so no buttons need to be tapped, just input your values and the calculations will be made when enough data is available.
The images should explain how it all works but feel free to ask any questions.