Par Card Guides
How your golf handicap index is calculated
Your handicap index is the average of the best 8 score differentials from your most recent 20 rounds. A score differential adjusts each round for the difficulty of the tees you actually played, using course rating and slope rating, so a 92 around a brutal set of tees can count better than an 88 around an easy one.
The formula in one line
Every round you post becomes a single number called a score differential, and your index is an average of your best recent ones.
Handicap index = average of the lowest 8 differentials from your last 20 rounds
The 113 is not arbitrary: it is the slope rating of a course of standard difficulty, so dividing by the slope you played and multiplying by 113 restates your round in standard-course terms.
What course rating and slope rating mean
They are two different measurements of difficulty, and they are printed on the scorecard for each set of tees. Course rating is the score a scratch golfer is expected to shoot from those tees, so it is usually a number close to par. Slope rating measures how much harder the course plays for a bogey golfer than for a scratch golfer, and it is where the 113 comes from.
Because both are tee-specific, the same course gives you different numbers from the tips than from the forward tees. Posting a round against the wrong tee is the most common way people end up with an index that does not match their game.
Adjusted gross score, not raw score
Handicap systems cap what any single hole can do to your index. The usual cap is a net double bogey: par, plus two strokes, plus any handicap strokes you receive on that hole. One blow-up hole therefore costs you a bounded amount rather than skewing your whole index.
Turning your index into a course handicap
Your index is portable; the number of strokes you actually get on a given day is not. To convert, scale the index by the slope of the tees you are playing and then adjust for how far the course rating sits from par.
| Slope rating | Relative difficulty | A 15.0 index scales to about |
|---|---|---|
| 105 | Easier than standard | 14 |
| 113 | Standard | 15 |
| 125 | Harder than standard | 17 |
| 135 | Difficult | 18 |
| 145 | Very difficult | 19 |
Slope ratings run roughly from the mid-50s to the mid-150s, with most everyday courses landing somewhere in the 110s to 130s. The practical takeaway: the same index earns you more strokes the harder the tees, which is the entire point of the system.
How many rounds do you need?
You do not need 20 rounds to get a number. Most handicap systems will issue an index once you have posted around three rounds' worth of holes, then use a smaller sample of your best differentials while your record fills in, widening toward the best 8 of 20 as you play more. Expect an early index to move a lot, since one good or bad round is a large share of a short record.
Why your index is lower than your average score
This surprises a lot of golfers. An index is built from your better rounds, not your typical ones, so it represents your demonstrated potential rather than what you shoot on a normal Saturday. Playing to your handicap is genuinely hard; most golfers do it a minority of the time, and shooting several strokes above your course handicap is completely ordinary.
How Par Card handles it
Par Card computes a WHS-style handicap index from the rating and slope of the tee you select, so the scorecard already knows which tees you played and how far each hole is from them. The stats dashboard charts that index over time alongside scoring average, hole-by-hole heatmaps, and course breakdowns, which makes it easy to see whether the trend is real or just a good week. It is a personal index for tracking your own progress, not a number issued by a handicap authority.
Track your index automatically
Par Card builds a WHS-style handicap index from the rounds you already score, using your tee's rating and slope. Scoring is free forever.