A Handicap Index is a portable number that represents your demonstrated golfing ability. Under the World Handicap System (WHS), it is calculated using the average of the best 8 Score Differentials from your most recent 20 rounds. If you have fewer than 20 rounds, a scaled-down table determines how many of your best scores are used, with small adjustments applied for very small sample sizes (3–6 rounds). The formula for each Score Differential is:

Score Differential = (113 ÷ Slope Rating) × (Adjusted Gross Score − Course Rating − PCC)

The resulting Handicap Index is rounded to one decimal place.

The 8/20 rule is the core of the WHS calculation. When you have 20 or more recorded rounds, your Handicap Index is based on the average of your 8 lowest Score Differentials from those 20 most recent rounds. This ensures your handicap reflects your potential ability rather than your average performance. For fewer than 20 rounds, a proportional sliding scale is used (see the table in the next FAQ).

Rounds	Lowest Differentials Used	Adjustment
3	1	−2.0
4	1	−1.0
5	1	0
6	2	−1.0
7–8	2	0
9–11	3	0
12–14	4	0
15–16	5	0
17–18	6	0
19	7	0
20	8	0

The adjustment for 3, 4, and 6 rounds is a conservative measure to prevent artificially low Handicap Index values based on very limited data.

PCC (Playing Conditions Calculation) is an adjustment made to account for abnormal weather or course conditions on a given day. It is automatically calculated by the WHS system based on all scores submitted at a course that day. For individual calculations, PCC is usually 0 under normal conditions. It can range from −1 (easier conditions) to +3 (extremely difficult conditions). If you do not know your PCC for a round, leave it at the default of 0.

Course Rating represents the expected score for a scratch golfer (0 handicap) under normal conditions. It is usually between 67.0 and 77.0 and is expressed with one decimal place.

Slope Rating measures the relative difficulty of the course for a bogey golfer (approximately 20 handicap for men, 24 for women) compared to a scratch golfer. The neutral value is 113, and the range is 55–155. A higher slope means the course is disproportionately harder for less skilled players.

The number 113 is the standard Slope Rating designated by the USGA and WHS as the neutral reference point. It represents the slope of a course of average relative difficulty. By dividing 113 by the actual Slope Rating of the course you played, the formula normalizes your score to a standard difficulty level, making your Score Differential comparable across any course worldwide.

An Adjusted Gross Score is your total strokes for a round after applying any hole-by-hole adjustments required by WHS rules. The most common adjustment is the net double bogey limit: on any hole, the maximum score you can record for handicap purposes is a double bogey plus any handicap strokes you are entitled to on that hole. This prevents a single disastrous hole from unfairly inflating your Handicap Index.

The Soft Cap and Hard Cap are safeguards that limit how quickly a Handicap Index can rise over a 12-month period, protecting the integrity of the system. The Soft Cap slows the upward movement when a player's Index rises more than 3.0 strokes above their 12-month low. The Hard Cap prevents the Index from rising more than 5.0 strokes above that low. These caps are automatically applied by official WHS systems and are not included in this basic calculator.