Golf Handicap Calculator estimates a Handicap Index from a list of recent rounds, using each round's score, course rating and slope rating. Add a row per round and it works out the score differential for each one — (score − course rating) × 113 ÷ slope rating — then averages your best differentials, the number of which depends on how many rounds you have entered, and multiplies by 0.96 for a simplified World Handicap System (WHS) style estimate. It is handy for casual golfers who want a quick sanity check on where their game stands between official updates, or anyone curious how the WHS formula actually works. Everything runs locally in your browser — your scores are never uploaded anywhere.
Features
Editable list of rounds — score, course rating and slope rating per row
Computes the WHS score differential for each round: (score − rating) × 113 ÷ slope
Automatically averages the best differentials based on how many rounds you have
Applies the 0.96 multiplier used in the official Handicap Index formula
Shows valid round count and how many differentials were used in the average
Add or remove rounds instantly as you enter more scores
Copy a plain-text summary of every differential and the final index
Runs entirely in your browser — no scorecards are uploaded
How to use the Golf Handicap Calculator
Enter the score, course rating and slope rating for each recent round
Add more rounds with 'Add round' — the differentials update live
Check each round's score differential in the row
Read the estimated Handicap Index and how many differentials it used
Example
Input
5 rounds
Output
Handicap index: 12.4
Common errors & troubleshooting
Handicap index looks far higher or lower than expected. — Double-check the slope rating — it usually runs 55 to 155 (113 is average). A slope typed as a course rating (or vice versa) will badly skew the score differential.
Result shows only one differential being used with several rounds entered. — The Golf Handicap Calculator follows the WHS table: with 5 or fewer rounds, only the single best differential counts — add more rounds so more of them are averaged.
A row's differential shows a dash instead of a number. — That round is missing a score, course rating, or slope rating, or the slope is 0 or negative — fill in all three fields for that round.
Index does not match an official club handicap. — This is a simplified estimate. The official WHS also applies a Playing Conditions Calculation and caps that this calculator does not model.
Frequently asked questions
How does the Golf Handicap Calculator estimate my Handicap Index?
It computes a score differential for each round — (score − course rating) × 113 ÷ slope rating — then averages your best differentials (the count depends on how many rounds you enter) and multiplies by 0.96, following the simplified structure of the World Handicap System formula.
How many rounds do I need to enter for an accurate estimate?
You can enter as few as one round, but the formula is designed for a rolling set of recent scores. With 20 rounds on file it uses the best 8 differentials, matching how WHS handicaps stabilize over more rounds.
What is a score differential in this golf handicap index calculator?
It is a single round's score adjusted for course difficulty: (score − course rating) × 113 ÷ slope rating. Lower differentials represent better rounds relative to how hard the course played.
Is this the same as an official course handicap calculator?
No. This tool estimates the underlying Handicap Index from your differentials. An official course handicap also factors in a specific course's slope and par, and your governing body applies additional adjustments this calculator does not model.
Does the Golf Handicap Calculator upload my scorecards?
No. Every score, rating and slope you enter is processed locally in your browser and is never sent anywhere — nothing about your rounds leaves your device.
Where do I find my course rating and slope rating?
Both are printed on the scorecard for the tees you played, usually near the yardage totals — course rating is a number close to par (like 71.4) and slope ranges from 55 to 155.
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