Golf Handicap Index & Course Handicap Calculator (WHS)

Understanding the golf handicap calculator — concept and principle

A Handicap Index is a portable measure of a golfer's demonstrated ability under the World Handicap System (WHS). It lets players of different skill compete fairly, and it converts into a Course Handicap: the number of strokes you receive on a specific set of tees. Use this calculator to estimate both.

Only the lowest two of eight differentials count; slope and rating then turn the 11.4 index into 13 strokes.

How it is calculated

Sort your most recent score differentials (up to 20) from lowest to highest.
Average the lowest ones: 8 of 20, or fewer when you have fewer rounds (3 rounds: lowest 1 minus 2.0; 4: lowest 1 minus 1.0; 5: lowest 1; 6: lowest 2 minus 1.0; 7–8: lowest 2; 9–11: 3; 12–14: 4; 15–16: 5; 17–18: 6; 19: 7).
Round the result to the nearest tenth: that is the Handicap Index.
Course Handicap = Handicap Index × (Slope ÷ 113) + (Course Rating − Par), rounded to a whole number.

The principle

WHS measures potential, not average. Taking the best part of your recent rounds shows what you can shoot on a good day, which keeps matches competitive. Slope Rating describes how much harder a course plays for a bogey golfer than for a scratch golfer; 113 is the standard slope, so a slope above 113 gives you more strokes. The (Course Rating − Par) term converts strokes relative to the rating into strokes relative to par, the way you play a round.

Worked example

Defaults: differentials 12.1, 14.5, 10.8, 15.2, 13.3, 11.9, 16.0, 12.7; slope 128; course rating 71.8; par 72.

Eight differentials: use the lowest 2, no adjustment. Sorted, the lowest are 10.8 and 11.9.
Average = (10.8 + 11.9) ÷ 2 = 11.35.
Rounded to the nearest tenth, as the WHS rules require: Handicap Index 11.4.
Course Handicap = 11.4 × 128 ÷ 113 + (71.8 − 72) = 12.91 − 0.2 = 12.71, rounded to 13.

How to read the result

A lower index means a better player; 0 is scratch and the maximum is 54.0. Your Course Handicap changes with each set of tees, because slope and rating differ. In competition the committee may also apply a handicap allowance (for example 95% in individual stroke play) to get your Playing Handicap.

Common mistakes

Entering gross scores instead of score differentials.
Using the average of all rounds instead of the lowest ones.
Using the slope or rating of the wrong tees or gender.
Forgetting that official indexes also include caps and adjustments.

Keep in mind: This is an estimate. An official Handicap Index is issued by your national golf association and includes the soft cap and hard cap on increases, exceptional score reductions and rounding that are not modelled here.

Frequently asked questions

How many rounds do I need for a Handicap Index?

Under WHS you need scores totalling 54 holes, for example three 18-hole rounds or a mix of 9- and 18-hole rounds.

Why is my Course Handicap higher than my index?

The course slope is above 113, or the course rating is above par, or both. On an easier course it can be lower than your index.

How often is the index updated?

Daily under WHS, after you submit a new acceptable score.

Sources: Rules of Handicapping (World Handicap System), USGA and The R&A

Checked 8 Nov 2026. Official league / federation formulas where they exist; widely used community formulas otherwise. For fun and analysis — not betting advice.

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