Each round produces a score differential — your adjusted score minus the course rating, scaled by the course's slope. Your official handicap index is the average of your best recent differentials; this tool works out one round's differential.
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Frequently asked questions
What is the differential formula?
Differential = (adjusted gross score − course rating) × 113 ÷ slope rating.
How does that become a handicap?
Your handicap index averages your lowest differentials from your recent rounds (currently the best 8 of 20).