I'm afraid you're actually asking an impossible question. Battery capacity is only one factor. You mentioned the processor as well, which is good, but medium usage is exceptionally difficult to define. And is that usage with phone calls, mobile data (mobile radios use quite a bit of juice), wifi data (wifi radio is much more efficient), gaming (which isn't efficient at all), watching videos (which isn't processor-intensive but does keep the display on, and the display is pretty much always the largest battery drainer), listening to music (which doesn't keep the display on but does keep the device awake), etc?
There are so many variables that it's not really feasible to make an estimate based just upon the capacity of the battery.
What phone in particular are you looking at? I could move your query into the forum specific to that device and get some fellow users to chime in with real-world usage. :thumbup: