Enter your recent golf scores and course details to estimate your GHIN handicap.
Your Estimated Handicap Index:
—
Understanding the GHIN Golf Handicap System
The GHIN (Golf Handicap and Information Network) system, managed by the USGA (United States Golf Association), provides golfers with a standardized way to measure their playing ability relative to the challenges of different golf courses. A handicap index allows golfers of varying skill levels to compete fairly against each other.
How Your Handicap Index is Calculated
The calculation of a handicap index involves a few key steps, primarily focusing on your recent scores and the difficulty of the courses you played:
Score Differential: For each eligible score, a "score differential" is calculated. This normalizes your actual score based on the course's difficulty. The formula is:
Score Differential = (Adjusted Gross Score – Course Rating) x (113 / Slope Rating) The '113' is the average slope rating for a standard golf course.
Best Score Differentials: The GHIN system typically looks at your 3 to 5 best score differentials from your most recent 20 scores. The exact number depends on how many scores you have in your record. For example, if you have between 3-4 scores, it uses the best 1 differential; 5-6 scores, the best 2; 7-8 scores, the best 3, and so on, up to 20 scores where it uses the best 8.
Average of Best Differentials: The handicap index is then calculated as the average of these selected best score differentials.
Rounding: The final handicap index is typically truncated (not rounded) to one decimal place.
Key Terms Explained:
Adjusted Gross Score (AGS): This is your gross score for a round, adjusted for Equitable Stroke Control (ESC) or net double bogey, whichever is more forgiving. It limits the maximum score on any hole.
Course Rating: A measure of the playing difficulty of a course for a scratch golfer (an expert golfer with a handicap of 0) under normal course and weather conditions. It's expressed in strokes and is generally around par.
Slope Rating: A measure of the relative difficulty of a course for a player who is NOT a scratch golfer compared to a scratch golfer. A higher slope rating indicates a more difficult course for the average golfer.
Why Use a Handicap Calculator?
While the official GHIN system is managed by golf associations, online calculators like this can help you:
Estimate your current handicap index.
Understand how individual scores impact your handicap.
Track your progress over time.
Prepare for tournaments or casual games where handicaps are used for fair competition.
Remember that this calculator provides an estimation. For an official USGA Handicap Index, you must join an authorized golf club or association.
function addScoreInputs() {
var numScores = parseInt(document.getElementById("numScores").value);
var scoreInputsDiv = document.getElementById("scoreInputs");
scoreInputsDiv.innerHTML = "; // Clear existing inputs
if (isNaN(numScores) || numScores 20) {
numScores = 5; // Default to 5 if invalid
document.getElementById("numScores").value = 5;
}
for (var i = 0; i < numScores; i++) {
var div = document.createElement('div');
div.className = 'input-group';
div.innerHTML = '' +
";
scoreInputsDiv.appendChild(div);
}
}
function calculateHandicap() {
var numScores = parseInt(document.getElementById("numScores").value);
var courseRating = parseFloat(document.getElementById("courseRating").value);
var slopeRating = parseFloat(document.getElementById("slopeRating").value);
var errorMessageDiv = document.getElementById("errorMessage");
errorMessageDiv.textContent = "; // Clear previous errors
var scoreDifferentials = [];
// Validate course and slope ratings
if (isNaN(courseRating) || courseRating <= 0) {
errorMessageDiv.textContent = "Please enter a valid Course Rating.";
return;
}
if (isNaN(slopeRating) || slopeRating = 155) { // Standard Slope Rating range
errorMessageDiv.textContent = "Please enter a valid Slope Rating (typically between 55 and 155).";
return;
}
for (var i = 0; i < numScores; i++) {
var scoreInput = document.getElementById("score" + i);
var score = parseFloat(scoreInput.value);
if (isNaN(score) || score = 3 && numScores = 5 && numScores = 7 && numScores = 9 && numScores = 11 && numScores = 13 && numScores = 15 && numScores = 17) { // 17-20 scores
numDifferentialsToAverage = 8;
} else { // Less than 3 scores
errorMessageDiv.textContent = "You need at least 3 scores to calculate a handicap index.";
return;
}
// Ensure we don't try to average more differentials than we have
if (numDifferentialsToAverage > scoreDifferentials.length) {
numDifferentialsToAverage = scoreDifferentials.length;
}
var sumOfBestDifferentials = 0;
for (var i = 0; i < numDifferentialsToAverage; i++) {
sumOfBestDifferentials += scoreDifferentials[i];
}
var handicapIndex = sumOfBestDifferentials / numDifferentialsToAverage;
// Truncate to one decimal place (GHIN standard)
handicapIndex = Math.floor(handicapIndex * 10) / 10;
document.getElementById("calculatedHandicap").textContent = handicapIndex.toFixed(1);
}
// Initialize score inputs when the page loads
window.onload = addScoreInputs;
// Also update inputs if the number of scores changes
document.getElementById("numScores").addEventListener("change", addScoreInputs);