i find on TM tournement greens
take the distance add or minus the elevation or depression then multiply by 0.80.6
ie. 20 feet 3 inches up (20+3) times .80 =18.4 feet
20 feet 3 inches down (20-3)times 0.80=13.6 feet
as long as on line will put you within 3 feet 95%+ of the time