Rule of thumb I use for Tourney Greens : (dist in feet +/- elev change in inches) less 20%.
Easy and quick to do in your head: 13 ft, up 2 in=15, less the 20% (3), so hit it 15-3 =12 ft.
same formula holds for other speeds, just change the %
If the elev is anything more than +/-2 then add or subtr an add'l foot or so.
Not perfect, but it will get you close