Dunno about a calculus but it outcome is quite straight ball-wise: more feel=higher price = slower meter. This will work with your Starters as well as with custom clubs. Tour-SD play faster than the Callies, Nikes and other expensive balls are slower (Starter balls are the fastest AFAIR).
OTOH, the better and more expensive balls are wasted, sort of, with your clubs. Consider the one-time investment in a decent club set, driver, 3WD and irons, perhaps the G20s at level 59 (88.000 XPs). Add a third wedge and you are ready for Master!