How Duffers handicaps are determined and adjusted

Before going any further, you may find it helpful to read our introductory page to Duffers handicaps, where the main differences between the Duffers system and the various official systems are described, and the reasons for the differences explained.

In short, Duffers handicapping is different because the official systems are geared towards good play, and ignore the realities of golf as played by Duffers. The mechanics of Duffers handicapping can be summarised as follows:

The Duffer keeps his actual gross score (GS), which is the total number of shots taken, without any 'capping' of the score on bad holes.
28 strokes are added to the course par to give the Duffers Scratch Score (DSS).
GS minus DSS give the Gross to Scratch score (GTS), the number by which the Duffer has exceeded the DSS.
The Duffer adds together his last three GTS to get the Cumulative to Scratch Score (CTS).
The Duffer divides the CTS for his last three rounds by three, to get his Average to Scratch Score (ATS).
The Duffer subtracts his current Exact Handicap (EH) from his ATS, to calculate the Net Differential (ND).
The ND is divided by three to give the Handicap Adjustment (HA) applicable to the EH, based on the last three rounds played. This gives the New Exact Handicap (NEH) which the Duffer will use for his next game.
For playing purposes (Match play, Stroke play or Stableford), the EH is rounded up or down to the nearest whole number to give the Duffers Playing Handicap (PH).
A Duffers handicap is not official until three cards have been completed. Before that, the handicap will be computed on the basis of one or two rounds, but the handicap is considered provisional and is not eligible for use in Duffers competitions.

In case the above should seem complicated, we append below an actual series of 15 rounds played by a Duffer on various courses, and demonstrate the evolution of his handicap.

Certain additions or subtractions may appear incorrect due to rounding to one decimal place, but all handicaps will be calculated this way by the computer. A pre-formatted Excel spreadsheet is available at no charge on request by e-mail from the Club Secretary.

Rd.	GS	DSS	GTS	CTS	ATS	EH	PH	ND	HA	NEH
1	114	100	14	14	14.0	12.0	12	2.0	0.7	12.7
2	111	100	11	25	12.5	12.7	13	-0.2	-0.1	12.6
3	115	100	15	40	13.3	12.6	13	0.7	0.2	12.9
4	112	99	13	39	13.0	12.9	13	0.1	0.0	12.9
5	110	100	10	38	12.7	12.9	13	-0.2	-0.1	12.8
6	105	100	5	28	9.3	12.8	13	-3.5	-1.2	11.7
7	111	98	13	28	9.3	11.7	12	-2.3	-0.8	10.9
8	109	99	10	28	9.3	10.9	11	-1.6	-0.5	10.4
9	112	100	12	35	11.7	10.4	10	1.3	0.4	10.8
10	122	100	22	44	14.7	10.8	11	3.9	1.3	12.1
11	114	100	14	48	16.0	12.1	12	3.9	1.3	13.4
12	117	97	20	56	18.7	13.4	13	5.3	1.8	15.2
13	120	99	21	55	18.3	15.2	15	3.2	1.1	16.2
14	118	100	18	59	19.7	16.2	16	3.5	1.2	17.4
15	116	97	19	58	19.3	17.4	17	2.0	0.7	18.0

Guide to abbreviations:
Rd.	=	Round (or official scorecard) number
GS	=	Gross Score for the round
DSS	=	Duffers Scratch Score, equal to the course's par plus 28
GTS	=	Gross to Scratch Score; the difference between the actual gross score and the Duffers Scratch Score for the course (par + 28 shots)
CTS	=	Cumulative to Scratch Score, being the total of the Gross to Scratch differences of the last 3 rounds
ATS	=	The Average To Scratch, equivalent to the Cumulative to Scratch Score divided by 3
EH	=	The Exact Handicap, as calculated after the last official round played
PH	=	The Playing Handicap, equivalent to the exact handicap rounded to the nearest integer (33.4 =33, 33.5 = 34)
ND	=	The Net Differential between the average to scratch and the exact handicap
HA	=	The Handicap Adjustment, equivalent to one-third of the net differential
NEH	=	The New Exact Handicap, equivalent to the previous exact handicap plus the handicap adjustment. This is the exact handicap for the Duffers next round.