Put in your last 5 to 20 scores and we will run the real World Handicap System maths on them. You will find out your actual Handicap Index, why you never shoot it, and whether the number you tell people is a vanity project or an outright con. Runs entirely in your browser — nothing is uploaded anywhere.
Enter your last 5 to 20 rounds and this free WHS handicap calculator returns your true index from the average of your best score differentials.
The Handicap Lie Detector is a free online WHS handicap calculator that applies the official World Handicap System score differential formula — (113 ÷ slope) × (adjusted gross − course rating) — to your recent rounds. It then compares the number you tell people against the number your scorecards support. If you want to calculate your golf handicap now, you need five rounds minimum. If you are understanding how handicap index is calculated and why you never seem to play to it, the lookup table and full method are shown below the result.
The number you give on the first tee. Be honest about what you claim, we will handle the rest.
Minimum 5 rounds, maximum 20 — that is what the World Handicap System uses. Leave rating and slope blank and we will assume a standard par-72 course of 113 slope.
Highlighted rows are the differentials actually counted toward your index.
Every round becomes a Score Differential: (113 ÷ Slope Rating) × (Score − Course Rating). That converts a score shot on any course, of any difficulty, into a single comparable number. Your Handicap Index is then the average of your lowest differentials — 8 of your last 20 once you have a full record.
This is the part almost nobody understands. Your handicap is built from your best 8 rounds out of 20. It is a measure of your potential, not your average. Most golfers play to their index roughly one round in five. If you shoot it every week, you are not a good golfer — you are a bandit.
A vanity handicapper claims a lower number than the maths supports, then quietly donates money every Saturday. A bandit claims a higher number than the maths supports and takes it. Both are lying. Only one of them is profiting.
The World Handicap System scales how many differentials it counts: with 5 rounds it uses your single lowest, with 6 it uses the lowest 2 minus an adjustment, and it climbs from there until you reach the full 8 of 20.
Each round produces a Score Differential of (113 / Slope Rating) x (Adjusted Gross Score - Course Rating). Your Handicap Index is the average of the lowest differentials from your most recent 20 scores, using 8 of 20 when you have a full record.
Because a handicap measures your potential, not your average. It is built from your best 8 rounds out of 20, so most golfers only play to their Handicap Index roughly one round in five.
A minimum of 54 holes, which is three 18-hole rounds. With 5 rounds only the single lowest differential is used, and the number of differentials counted rises as you post more scores until 8 of 20 is reached.