Each round becomes a Score Differential: 113 divided by the Slope Rating, times your adjusted gross score minus the Course Rating minus the PCC adjustment. Your Handicap Index is the average of the 8 lowest differentials among your 20 most recent, rounded to the nearest tenth (Rule 5.2b). The calculator below does both steps for you.
The FormulaWhat goes into a Score Differential
Score Differential = (113 / Slope Rating) x (Adjusted Gross Score - Course Rating - PCC adjustment). The example column uses made-up numbers for one round: an adjusted gross score of 90 on tees with a Course Rating of 71.2 and a Slope Rating of 125, on a day with no PCC adjustment.
| Piece | What it is | Example |
|---|---|---|
| Adjusted Gross Score | Your gross score with each hole capped at net double bogey: par + 2 + any handicap strokes you get on the hole (Rule 3.1b). Before you have an Index, the cap is par + 5 (Rule 3.1a). | 90 |
| Course Rating | The expected score of a scratch player on those tees, to one decimal. | 71.2 |
| PCC adjustment | The day's playing conditions calculation: -1.0, 0.0, +1.0, +2.0 or +3.0. It is zero when fewer than eight acceptable scores are submitted that day (Rule 5.6). | 0.0 |
| Slope Rating | Relative difficulty for a bogey golfer. Standard difficulty is 113. | 125 |
| 113 / Slope Rating | The scaling step. Above 113 shrinks the result; below 113 stretches it. | 113 / 125 = 0.904 |
| Score Differential | 0.904 x (90 - 71.2 - 0) = 0.904 x 18.8 = 16.9952, shown to one decimal. | 17.0 |
Source: USGA, Rules of Handicapping FAQs, "What is a Score Differential"; R&A, Rules of Handicapping, Rules 3.1 and 5.6 and Appendix G. The example numbers are our own.
The CalculatorEnter your rounds, get your Handicap Index
Use 18-hole rounds. Take the adjusted gross score, Course Rating and Slope Rating for the tees you played, and the PCC adjustment shown for that round in your scoring record (leave it at 0.0 if you do not have one). You can enter up to 20 rounds. The rounds that count toward your Index are marked as you type.
Handicap Index
n/a
Add at least 3 complete rounds.
How it was worked out
Each round needs an adjusted gross score, a Course Rating and a Slope Rating.
This tool does not apply the soft cap, the hard cap or the exceptional score reduction, so an official Index can differ. See which rounds count for your handicap.
Fewer than 20How many differentials count at each number of scores
Once you have 20 scores, the Index is the average of the lowest 8. Before that, the rule uses fewer differentials, and at a few counts it subtracts an adjustment. The result is rounded to the nearest tenth. The calculator follows this table.
| Score Differentials in your record | Differentials used | Adjustment |
|---|---|---|
| 3 | Lowest 1 | -2.0 |
| 4 | Lowest 1 | -1.0 |
| 5 | Lowest 1 | 0 |
| 6 | Average of lowest 2 | -1.0 |
| 7 or 8 | Average of lowest 2 | 0 |
| 9 to 11 | Average of lowest 3 | 0 |
| 12 to 14 | Average of lowest 4 | 0 |
| 15 or 16 | Average of lowest 5 | 0 |
| 17 or 18 | Average of lowest 6 | 0 |
| 19 | Average of lowest 7 | 0 |
| 20 | Average of lowest 8 | 0 |
Source: R&A, Rules of Handicapping, Rule 5.2a, table for fewer than 20 scores.
A first Index calculated above 54.0 is set to 54.0 (Rules 5.2a and 5.3). A negative result is a plus Handicap Index (Rule 5.2c), which the calculator shows with a plus sign.
Using itHow to use the calculator
Enter your most recent rounds, up to 20. For each one you need four things: the adjusted gross score, the Course Rating and Slope Rating for the tees you played, and the PCC adjustment for that day. Your scorecard or club lists the ratings for each set of tees, and our guide to reading a golf scorecard shows where they sit on the card.
Each round shows its differential as you type, and the rounds that count toward the Index are marked "(counts)". The Index appears once you have 3 complete rounds. To turn an Index into strokes on a particular course, use the Course Handicap calculator.
Only 18-hole rounds work here. A 9-hole score gets an 18-hole Score Differential in your scoring record, and that is the number to carry over.
Watch forCommon mistakes
Entering your raw gross score. The formula uses the adjusted gross score, with any hole above net double bogey brought down to it (Rule 3.1b). A round with one blow-up hole gives a different differential if you skip that step.
Using par instead of the Course Rating. The differential subtracts the Course Rating, which is usually not equal to par. Par matters for the Course Handicap, not here.
Averaging the wrong scores. The Index uses the lowest 8 differentials among your most recent 20, not your 8 best ever. A score stays in the 20 however old it is, until newer scores push it out (Rule 5.5).
Ranking rounds by raw score. Two rounds with the same adjusted gross score can have different differentials, because the Course Rating, Slope Rating and PCC differ. Rank by differential.
Expecting a match with your app. Your official Index can also be moved by the soft cap and hard cap (Rule 5.8), an exceptional score reduction (Rule 5.9) and Committee adjustments. This calculator leaves those out. Our guide to which rounds count covers what can go into your record.
FAQQuick answers
How is a Handicap Index calculated?
Each round is turned into a Score Differential: (113 / Slope Rating) x (Adjusted Gross Score - Course Rating - PCC adjustment). With 20 scores, the Index is the average of the lowest 8 of your most recent 20 differentials, rounded to the nearest tenth (Rule 5.2b).
How many rounds do I need before I get a Handicap Index?
The USGA says a total of 54 holes must be played and posted, in any mix of 9-hole and 18-hole rounds (Rule 4.5). The R&A table for fewer than 20 scores starts at 3 Score Differentials (Rule 5.2a).
What is the PCC adjustment?
The playing conditions calculation checks whether the course played harder or easier than normal that day. It can be -1.0, 0.0, +1.0, +2.0 or +3.0, it applies to everyone's differentials for the day, and it is zero when fewer than eight acceptable scores are submitted (Rule 5.6). It appears in your scoring record.
Why does the Index use only the lowest 8 of 20 scores?
The Rules of Handicapping say a Handicap Index should represent your demonstrated ability (principle of Rule 5). Averaging the lowest 8 of your most recent 20 differentials is the method Rule 5.2b sets.
What does a plus Handicap Index mean?
When the Index calculates as a negative figure, it is a plus Handicap Index (Rule 5.2c). The calculator shows it with a plus sign, like +1.2. It belongs to a player better than scratch.
Where do I find the Course Rating and Slope Rating?
The Course Rating, Slope Rating and par for each set of tees must be readily available (Appendix G). Look on the scorecard or ask the pro shop, and see how to read a golf scorecard.