Don Porter Thursday Golf Group Index / Handicap Formulas

Utilizing consultations with the U.S.G.A, S.C.G.A., and some of the local area Course Professionals, The Committee has adopted the following formula to calculate each member’s DPTGG Index effective on June 1, 2004: As of October, 2021, the Committee has determined that rules changes put into place in 2016 by the R&A and USGA regarding handicaps notwithstanding, these formulas remain in effect for the DPTGG.

Each member will be categorized into either the Super Flight (9.4 index and under) or Porter Flight (9.5 index and over) based on his/her Established Group Index. This combined with gender and or special circumstances will determine a Player’s *Tee Assignment as follows.

Super Flight (Back Tees/Usually Blue) scores are converted using the Back Tee Course Rating and Slope. Porter Flight (Middle Tees/White and Forward Tees/Red) scores are converted using their respective Course Ratings and Slopes.

Each Adjusted Gross Score is entered into our database where it is converted to a differential by subtracting the U.S.G.A. Course Rating for the appropriate Tee Assignment. That figure is multiplied by the standard U.S.G.A. Slope of 113 and then rounded up or down to 1 decimal point (10^th).

USGA Course Rating of 71.5 and Slope Rating of 125 with an adjusted Gross of 95...

Adjusted Gross Score - USGA Course Rating:	95 - 71.5 = 23.5
Difference X Standard Slope:	23.5 X 113 = 2655.5
Result / USGA Slope Rating:	2655.5 / 125 = 21.24
Handicap Differential:	21.2

The following table is used to determine which scores are used to determine each player’s Group Index:

Number of Applicable Scores	Differentials Used
5 or 6	Lowest 1
7 or 8	Lowest 2
9 or 10	Lowest 3
11 or 12	Lowest 4
13 or 14	Lowest 5
15 or 16	Lowest 6
17	Lowest 7
18	Lowest 8
19	Lowest 9
20 or more	Lowest 10

The Member’s Established Index is then calculated by taking the Average of the Sum of Differentials for lowest of the most recent applicable rounds using the following formula:

With 20 or more rounds available:
Sum of applicable differentials:	204.7
Divided by applicable rounds:	204.7 ÷ 10 = 20.47
Multiply by .96:	20.47 X .96 = 19.6512
Delete digits after 10^ths:	19.6
D.P.T.G.G Handicap Index	19.6

Course Handicaps are then computed weekly based on each member’s established Index based upon his/her Tee Assignment/Flight _{(*see above)} using the following formula:

U.S.G.A. Course Slope Middle Tee Rating = 121
Member Index X Rating:	19.6 X 121 = 2371.6
Divided by Standard Slope:	2371.6 ÷ 113 = 20.98761
Rounded off (.5 or more rounded off upward)	21
Course Handicap:	21

Please note that there are certain minor calculation variations between the U.S.G.A. and the S.C.G.A. We have adopted our formulas using primarily the U.S.G.A. format. Any questions should be directed to the Handicap Chairman or the Rules Chairman.

Any Active Member may preview his/her Course Handicaps for each of our regular venues by logging into our website using his/her Username and Password and clicking on the “Course Index Converter” Button located on the top of the Player Profile Page.