What is a Score Differential?

Every round you post becomes one Score Differential. It’s what lets an 88 on a hard course and an 84 on an easy one be compared fairly.

The formula

Score Differential = 113 ÷ Slope Rating × (adjusted gross score − Course Rating − PCC)

• Adjusted gross score is your score after capping any hole above net double bogey.
• Course Rating is what a scratch golfer is expected to shoot on those tees. The gap between your score and it is how many strokes worse than scratch you played.
• 113 ÷ Slope Rating scales that gap to a course of standard difficulty. On tees harder than standard (Slope above 113), the same gap counts for less.
• PCC is the playing conditions calculation, usually 0. It moves when a course plays much harder or easier than normal that day.

The result is rounded to one decimal, with .5 rounding up.

Two examples

Round	Score	Course Rating	Slope	Differential
A	88	72.4	131	113 ÷ 131 × 15.6 = 13.5
B	84	69.1	117	113 ÷ 117 × 14.9 = 14.4

Round A is four strokes higher, but on a harder course, so it was actually the better round for handicap purposes.

Negative differentials

Scoring better than the Course Rating gives a negative differential, which counts like any other. A negative value rounds toward zero at .5: −1.55 becomes −1.5.

How differentials make your Handicap Index

Your Handicap Index is the average of your lowest 8 differentials out of your most recent 20. With fewer rounds, fewer count: see the table on the handicap calculator page.

9-hole rounds

Since 2024, a 9-hole score is combined with an expected score for the other 9 holes, based on your current Handicap Index, to make an 18-hole differential. That needs your official record, so our calculator works with 18-hole rounds only.