Wandering Golf

How handicap works.

We follow the World Handicap System. Here is exactly what we calculate, what we don't yet calculate, and how it compares to other golf apps.

What a handicap actually is

A Handicap Index is a number that estimates your potential scoring ability. It lets you play a round against someone with a different skill level on equal footing, and it lets you measure your own progress over time. Lower is better. A scratch golfer has a Handicap Index of 0.0. A 20 handicap shoots, on average, about 20 strokes over a course's rating from the tees they play.

The World Handicap System (WHS) is the global standard, jointly governed by the USGA and The R&A since 2020. It replaced the old USGA Handicap System and unified handicap rules across countries. Wandering Golf follows WHS.

The formula we use

For every round, we compute a Score Differential:

Score Differential = (113 / Slope Rating) × (Score − Course Rating)

Three inputs:

  • Score: your gross score for the round. Today we use the raw gross score. WHS calls for an Adjusted Gross Score (with Net Double Bogey applied per hole); see what we currently apply below.
  • Course Rating: the score a scratch golfer is expected to shoot from those tees. Set by the local golf association.
  • Slope Rating: how much harder the course plays for a bogey golfer relative to scratch. The standard reference value is 113. Higher slope means a tougher course for the average player.

If we don't have rating data for a course you played, we default to a Course Rating of 71.0 and a Slope of 113. We surface this in the round detail so you know.

The lowest-8-of-20 sliding scale

Once you have a few rounds in the system, your Handicap Index is the average of a subset of your best Score Differentials from your most recent 20 eligible rounds. The exact subset depends on how many rounds you have:

Rounds availableDifferentials usedAdjustment
3Lowest 1−2.0
4Lowest 1−1.0
5Lowest 1None
6Lowest 2−1.0
7–8Lowest 2None
9–11Lowest 3None
12–14Lowest 4None
15–16Lowest 5None
17–18Lowest 6None
19Lowest 7None
20+Lowest 8None

Once you cross 20 rounds, only your most recent 20 are considered. Older rounds drop off as new ones come in. This is the same WHS sliding scale used by the USGA, R&A, and most national associations.

A worked example

Say you played 5 rounds and your scorecards look like this:

RoundScoreCourse RatingSlopeDifferential
18871.212814.8
29270.812519.2
38572.013111.2
49071.513016.1
58771.012714.2

With 5 rounds, the table tells us to use the lowest 1 differential with no adjustment. The lowest is round 3 at 11.2.

So your Handicap Index after 5 rounds = 11.2. As you play more rounds, the formula starts averaging more of your best ones, and your Index settles into something more representative of your real game.

What we currently apply (and what we don't)

We are explicit about this because some apps quietly cut corners on WHS rules without telling you. We don't.

Implemented today

  • Score Differential formula using Course Rating and Slope Rating
  • Lowest-8-of-20 sliding scale per the WHS table
  • Index range bounded between −10.0 and 54.0
  • Minimum 3 rounds required before an Index is published

On the roadmap (not yet applied)

  • Net Double Bogey per-hole maximum score cap. Today we use raw gross scores.
  • Playing Conditions Calculation (PCC) adjustment for unusually hard or easy weather and course conditions.
  • Soft Cap and Hard Cap protection that slows upward Index movement after a 3.0-stroke jump and caps the total annual increase at 5.0.
  • Exceptional Score Reduction (ESR) auto-reduction when a single round is 7.0 strokes better than your current Index.
  • 9-hole round combining. Today, only full 18-hole rounds are eligible; WHS supports pairing 9-hole rounds with another 9-hole or with an Expected Score.

Why the gaps? We chose to ship the core math correctly first and add the WHS adjustments incrementally with full transparency. If you need a strictly USGA-sanctioned official handicap for tournaments, you should still get one through your local golf association (we are not a licensed handicap authority). What we give you is a faithful, transparent estimate based on the same WHS math, useful for tracking your own progress and for honest match-play with friends.

Wandering Golf vs 18Birdies vs full WHS

A lot of golf apps publish a handicap number. Almost none of them follow WHS to the letter. Here's the honest comparison:

FeatureWandering Golf18BirdiesFull WHS
Score Differential formulaYes (WHS)Yes (WHS)Yes
Lowest 8 of last 20YesYesYes
Min rounds for Index313
Max Index54.0No cap54.0
Net Double Bogey adjustmentRoadmapMax Double Bogey onlyYes
PCC adjustmentRoadmapNoYes
Soft Cap / Hard CapRoadmapNoYes
Exceptional Score ReductionRoadmapNoYes
9-hole round combiningRoadmapScore × 2Pair with 9 or Expected Score

The point isn't that we're better than 18Birdies on every line today. The point is that we tell you what we apply. If your Index changes, you can read the math and see why.

Bonus: the practice handicap

On top of the official WHS Index from your scored rounds, we also estimate a handicap from your practice data. It scores 8 swing metrics from your launch monitor (carry, club speed, smash factor, contact consistency, club path, face control, direction, distance variance) against handicap-stratified benchmarks from published tour and amateur data.

This is not WHS, and we don't pretend it is. It's a side metric that answers a different question: based on how you're swinging the club at the range, what handicap should you actually be able to play to? Useful for spotting when your range game and your scoring game diverge, and for figuring out what to work on. If your practice handicap says 8 and your scoring handicap says 14, your problem is probably between the ears or in your short game, not your full swing.

Available via the analyze_handicap and get_handicap_breakdown MCP tools. See the MCP Tools Reference.

FAQ

How is my handicap calculated?

We use the WHS Score Differential formula (113 / Slope) × (Score − Course Rating) for every round, then average the lowest differentials from your last 20 rounds on a sliding scale that depends on how many rounds you have.

How many rounds do I need before I get a handicap?

Three. With 3 rounds we use the single lowest differential and subtract 2.0; with 4 we subtract 1.0; with 5 or more we follow the standard WHS table. Below 3 rounds you'll see "not enough rounds" instead of an Index.

What's the difference between Course Rating and Slope?

Course Rating is the score a scratch golfer is expected to shoot from a given set of tees. Slope is how much harder the course plays for a bogey golfer relative to scratch. A high slope means the course punishes the average player more than a low-slope course does.

What if a course has no rating data?

We default to Course Rating 71.0 and Slope 113. We surface this in the round detail so the differential is clearly an estimate, not a sanctioned calculation.

What's the maximum Handicap Index?

54.0, the same cap WHS sets for both men and women.

Can I use 9-hole scores?

Not yet. Today only full 18-hole rounds are eligible. WHS supports pairing two 9-hole rounds (or one 9-hole round plus an Expected Score from your current Index) into a synthetic 18, and we plan to ship that.

Is this an official handicap I can use in tournaments?

No. We are not a licensed handicap authority. For an official Index recognized at sanctioned events, get one through your local golf association (GHIN in the U.S., CONGU in the U.K., etc.). What we give you is a transparent estimate using the same WHS math, useful for tracking your own progress.

Why don't you apply Net Double Bogey, PCC, Soft Cap, Hard Cap, ESR?

They're on the roadmap. We chose to ship the core WHS formula first with full transparency rather than silently approximate. As we layer those adjustments in, this page will update and your Index will recompute against the new rules.

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