Way to calculate putting power for specific green speeds:
To get a speed factor you divide the number 9 by the green speed.
SLOW (7.4)...9 divided by 7.4 = 121.6% (roundup to 122)
STANDARD (7.9)...9 divided by 7.9, = 113.9% (114)
FAST (9) ...9 divided by 9, which is simply one to one, or 100%
VERY FAST (10)...9 divided by 10, = 90%
TOURNAMENT (11.)...9 divided by 11, = 81.8% (82)
TOURNAMENT (12)...9 divided by 12, = 75%
TOURNAMENT (13)...9 divided by 13 which is 69.23% (69)
For example, on a Tournament 12 green with a 20 foot putt that is 2 feet down one could calculate power needed as 20 - 2 = 18 * .75 = 13.5.