Calculate your World Handicap System index from your recent scores.
The World Handicap System (WHS), adopted globally in 2020, produces a portable handicap index that works on any course in the world. For each round you enter your adjusted gross score, the course rating, and the slope rating — both printed on the scorecard. The differential measures how well you played relative to the difficulty of that specific course. The system averages your best 8 of your most recent 20 differentials, then multiplies by 0.96. That 4% reduction exists because the WHS is designed to reflect scoring potential (a player's realistic best) rather than average performance.
Handicap Differential
Differential = (113 / Slope Rating) × (Adjusted Gross Score − Course Rating)
Handicap Index
Handicap Index = 0.96 × average of the best 8 (lowest) differentials of the most recent 20
Course Rating is the expected number of strokes a scratch golfer (handicap 0) would take on a course under normal conditions. Slope Rating measures the additional difficulty of the course for a bogey golfer relative to a scratch golfer. Slope ranges from 55 (very easy) to 155 (very hard); the standard is 113. Both values are on the scorecard.
Using only the best differentials anchors the index to a player's 'potential' rather than their average. This makes the system fairer in stroke-play competitions: a player who consistently plays to their best has an advantage over someone who only occasionally has a great round.
In the WHS, an adjusted gross score caps each individual hole score at Net Double Bogey (par + 2 + any handicap strokes received on that hole). Holes you don't complete are recorded as Net Double Bogey. This adjustment prevents one very bad hole from distorting the handicap.
The 0.96 multiplier (sometimes called the 'playing conditions calculation' factor) reduces the average by 4%, keeping the index aligned with scoring potential under tournament conditions rather than casual play. It is a fixed part of the WHS formula.