Most golfers are familiar with Handicap Index, the USGA’s indicator of overall playing ability. Although a similar measure of putting ability alone isn’t recognized by that golf organization, Strokes Gained: Putting can be converted to a useful Putting Handicap Index by making two assumptions:
First, because Strokes Gained: Putting values are based on the putting ability of PGA TOUR professional golfers, the conversion equates a Strokes Gained: Putting value of 0.0 to a Putting Handicap Index of +6.0. That is, if the average TOUR pro is assumed to play to a +6 overall handicap, then his average putting performance (i.e., Strokes Gained: Putting = 0.0) should also correspond to a Putting Handicap Index of +6.
Second, the conversion assumes that 20% of the difference in overall playing ability for PGA TOUR pros and typical golfers is due to their disparate putting skills. For example, a Putting Handicap Index of 14 (i.e., -14 for our purposes here) would correspond to a Strokes Gained: Putting value of -4.0: -[ (+6) - (-14) ] x 0.2 = -4.0 .
Combining the two assumptions above enables Strokes Gained: Putting to be transformed to Putting Handicap Index using the formula below:
Putting Handicap Index = (5 x Strokes Gained: Putting) + 6
TruPutt uses the above formula to determine the Putting Handicap Index that is displayed at the top of the History screen. As is the case for a standard Handicap Index, an average of the 10 lowest Strokes Gained: Putting values selected from the last 20 rounds is used for the calculation; the procedure is the same if only 11-19 rounds are accumulated. When just 10 or fewer rounds are available, all Strokes Gained: Putting values are averaged for the calculation. Furthermore, as is the convention for a standard USGA Handicap Index, the minus sign is removed from a negative Putting Handicap Index, while a plus sign is attached to a positive value (e.g., a Putting Handicap Index of -14 would be referred to as 14, and an index of 6 would be written as +6).
Unlike Strokes Gained: Putting, which is an unbiased measure of round-to-round putting performance, Putting Handicap Index is a subjective value due to the two assumptions noted above. Nevertheless, Putting Handicap Index can be a practical indicator of a player’s putting ability similar to the well known Handicap Index, which itself is based on subjective values of Course Rating and Slope.