Accurately calculate and understand the swing weight of your golf clubs.
Club Specifications
Weight of the club head in grams.
Weight of the shaft in grams.
Weight of the grip in grams.
Overall length of the club in inches.
Your Swing Weight Results
Component Weight Contribution: grams
Shaft Moment of Inertia Proxy:
Balance Point Contribution:
Swing Weight is calculated by determining the torque (rotational force) of the club head around the golfer's hands (which are assumed to be at the balance point). The formula used here is an approximation:
SW = (Club Head Weight – (Total Club Length – Balance Point) * Weight per Inch of Shaft) * 100
A more practical approach involves measuring the weight difference between the grip end and the balance point of the club, often converted to a D-scale.
Swing Weight vs. Component Weights
Swing Weight Component Analysis
Component
Weight (grams)
Contribution to Torque
Club Head
Shaft
Grip
Total Club Weight
–
Calculated Swing Weight
–
What is Swing Weight?
Swing weight is a crucial, yet often misunderstood, aspect of golf club fitting. It doesn't refer to the overall weight of the club, but rather the perceived "heft" or balance point of the club head relative to the golfer's hands. It's essentially a measure of the rotational force or torque generated by the club during the swing. Professional club fitters use swing weight to ensure consistency across a set of clubs, allowing golfers to achieve a smoother, more repeatable swing. Understanding and accurately measuring swing weight is paramount for optimizing performance, as it directly influences how a club feels and performs during your golf swing. Many amateur golfers focus solely on total club weight, neglecting the more nuanced effect of swing weight.
Who should use it?
Any golfer looking to improve their consistency and performance. This includes serious amateurs, competitive players, and even beginners who want to start with properly fitted equipment. Club builders and repair technicians also rely heavily on swing weight measurements to ensure clubs are built to spec and feel uniform.
Common misconceptions include confusing swing weight with total club weight or assuming that heavier clubs always mean a heavier swing weight. In reality, a lighter total club can have a heavier swing weight if the weight distribution is concentrated towards the club head. Another misconception is that a higher swing weight is always better; this is incorrect as the optimal swing weight is highly dependent on the individual golfer's strength, swing speed, and preferences.
Swing Weight Formula and Mathematical Explanation
The concept of swing weight is rooted in physics, specifically torque and moment of inertia. While specialized machines called swing weight scales are the standard for precise measurement, we can approximate the calculation using key club component weights and dimensions.
The core idea is to quantify how much force the club head exerts as it rotates around the golfer's hands. The farther the club head's mass is from the pivot point (the golfer's hands), and the heavier the club head, the greater the torque.
A simplified formula often used for approximation involves the following components:
Approximate Swing Weight Calculation:
First, we determine the weight of the club beyond the balance point. Let's call this the "effective club head weight" for our purposes, as it's the part contributing most to the rotational inertia.
Weight Beyond Balance Point = Club Head Weight - (Shaft Weight + Grip Weight) * (Balance Point / Total Club Length)
This isn't entirely accurate as it doesn't account for weight distribution along the shaft. A more direct calculation often seen in clubs building is:
Swing Weight = (Club Head Weight) - (Weight of shaft + grip distributed from butt to balance point)
A commonly cited formula for approximation, which our calculator uses and simplifies:
Simplified Formula Approximation:Effective Torque Factor = (Club Head Weight) - ( (Total Club Length - Balance Point) * (Shaft Weight + Grip Weight) / Total Club Length )
This factor, when multiplied by 100 and adjusted for the standard scale, gives an approximation.
For practical purposes and direct measurement, swing weight is typically expressed on a scale from A to G, with numbers indicating increments (e.g., D0, D1, D2). Each number represents approximately 2.77 grams of added weight at the butt end, or equivalently, a shift in the balance point. D0 is considered a common standard for many men's clubs.
Distance from the butt end to the shaft's balance point.
Inches (in)
18in – 25in
Swing Weight
The perceived heft of the club head relative to the hands.
Scale (e.g., D1, D2)
C0 – E9 (common range D0-D4)
Practical Examples (Real-World Use Cases)
Let's explore how changes in club components affect swing weight.
Example 1: Adjusting Driver Swing Weight
A golfer finds their current driver feels a bit too light, leading to inconsistent tempo. They have a driver with the following specs:
Club Head Weight: 205g
Shaft Weight: 65g
Grip Weight: 50g
Total Club Length: 45.5 inches
Balance Point: 23 inches
Using our calculator, we input these values. The calculator estimates an initial swing weight of approximately D3. The golfer wants to increase this to D5 to feel more head weight. They can achieve this by:
Adding weight to the club head (e.g., using lead tape). If they add 4 grams to the head, the new head weight is 209g. Recalculating yields approximately D4.5.
Switching to a lighter grip. If they switch to a 40g grip, the new grip weight is 40g. Recalculating yields approximately D3.5.
Switching to a heavier shaft. If they switch to a 70g shaft, the new shaft weight is 70g. Recalculating yields approximately D3.8.
The most effective method to increase swing weight is by adding weight to the club head or reducing weight closer to the grip. Adding weight directly to the head is the most common method for club builders and golfers.
Example 2: Ensuring Iron Set Consistency
A club builder is assembling a set of irons. They aim for a progression from C9 in the long irons to D2 in the short irons. They are building a 7-iron with the following components:
Club Head Weight: 265g
Shaft Weight: 75g
Grip Weight: 50g
Total Club Length: 37 inches
Balance Point: 20 inches
After assembly, the club weighs 440g. They measure the swing weight using a swing weight scale and find it to be D0. To reach the target D2, they know they need to add approximately 5.5 grams (2 increments * 2.77g/increment) of effective weight to the club head, or adjust the balance point. They might add 3 grams of lead tape to the sole of the club head and switch to a 47-gram grip. This would reduce the total weight slightly but increase the swing weight. After adjustments, the swing weight is measured at D2. The calculator helps verify that component choices are moving in the right direction, even if a precise scale is used for final tuning.
How to Use This Swing Weight Calculator
Our Swing Weight Calculator is designed for simplicity and accuracy. Follow these steps to get your results:
Gather Your Club's Specifications: You will need the precise weight of your club head (in grams), the shaft (in grams), the grip (in grams), the total length of the club (in inches), and the balance point of the shaft (in inches from the butt).
Enter the Data: Input each value into the corresponding field in the calculator. Ensure you are using the correct units (grams for weight, inches for length).
Calculate: Click the "Calculate Swing Weight" button.
View Results: The calculator will immediately display the estimated swing weight, along with key intermediate values like component weight contribution and balance point influence. A visual chart and a detailed table will also update to provide further insight.
Understand the Formula: Read the brief explanation of the formula used to grasp the underlying principles.
Interpret Your Results: Compare your calculated swing weight to typical ranges (e.g., D0-D4 for men's irons and drivers) and your personal feel. If the swing weight is too light or too heavy, you can experiment with changes to components (as shown in the examples) and recalculate.
Reset or Copy: Use the "Reset Defaults" button to clear your inputs and start over with standard values. Use the "Copy Results" button to easily share your findings or save them.
Decision-making guidance:
If your swing weight feels too light, consider adding weight to the club head or using a lighter grip. If it feels too heavy, you might need to reduce club head weight or use a heavier grip. Consistency across your set is key; strive for similar swing weights on clubs of similar types. For drivers and fairway woods, a slightly higher swing weight might be preferred for feel, while irons and wedges often benefit from a progression.
Key Factors That Affect Swing Weight Results
Several factors contribute to a golf club's swing weight and how it's perceived by the golfer. Understanding these can help in making informed adjustments:
Club Head Weight: This is the most significant factor. A heavier club head, all else being equal, will result in a higher swing weight because it exerts more rotational force. This is why drivers and fairway woods have significantly heavier heads than irons.
Total Club Length: Longer clubs naturally increase the leverage of the club head's weight, thus increasing swing weight. This is why a 46-inch driver will feel heavier in swing weight than a 45-inch driver with identical head, shaft, and grip.
Shaft Balance Point: The point at which the shaft balances indicates how the shaft's weight is distributed. A shaft with a balance point closer to the grip end (higher number on our calculator) effectively shifts more weight towards the club head, increasing swing weight. Conversely, a balance point closer to the tip lowers swing weight.
Grip Weight: A lighter grip reduces the overall club weight and also the weight at the butt end. This shifts the balance point closer to the head, thereby increasing the swing weight. Conversely, a heavier grip will decrease swing weight. This is a common adjustment for fine-tuning.
Component Material Density: Different materials used for heads (titanium, carbon composite, steel), shafts (graphite, steel), and grips have varying densities. Even at the same dimensions, a denser material will weigh more, affecting the overall club weight and swing weight. For example, graphite shafts are lighter than steel shafts, which impacts swing weight calculations.
Added Accessories (e.g., Lead Tape): Attaching lead tape to the club head is a popular method to increase swing weight. Even small amounts of weight added to the head have a pronounced effect on swing weight due to their distance from the pivot point. Conversely, adding weight to the butt end of the club would decrease swing weight.
Swing Speed and Strength (Golfer's Contribution): While not a direct factor in the calculation, the golfer's own physical attributes heavily influence their perception of swing weight. A golfer with a faster swing speed and greater strength might prefer a higher swing weight for a more solid feel, while a slower-swinging player might benefit from a lower swing weight for better control and tempo.
Frequently Asked Questions (FAQ)
What is the standard swing weight for golf clubs?
The most common swing weights for men's clubs range from D0 to D4. Drivers and fairway woods often fall in the D2-D4 range, while irons typically range from D0-D2. Women's clubs usually range from C6-C8 for woods and C5-C7 for irons. However, this is a guideline, and personal preference plays a significant role.
Can I change my swing weight myself?
Yes, you can adjust swing weight yourself. The most common methods include adding lead tape to the club head (increases swing weight), changing grip size or weight (heavier grip decreases, lighter grip increases), or using specific weights designed for the club head or hosel.
How does swing weight affect my game?
Swing weight significantly impacts your club's feel and consistency. A correct swing weight can lead to a more natural tempo, better control, and a more consistent strike. An incorrect swing weight can cause you to rush your swing (if too light) or feel restricted (if too heavy), leading to poor shot execution.
What's the difference between swing weight and total weight?
Total weight is the absolute mass of the entire golf club. Swing weight measures the perceived heft or rotational force of the club head relative to the golfer's hands, primarily influenced by the distribution of weight, not the total mass. You can have a lighter overall club with a heavier swing weight.
Should all clubs in my bag have the same swing weight?
Not necessarily. While consistency is important, there's often a slight progression. For example, drivers and fairway woods might be slightly heavier in swing weight than long irons, which might be slightly heavier than mid-irons, and so on. This progression helps maintain tempo through the set. However, large disparities can be detrimental.
My calculator shows a specific numerical value, but golf stores talk about 'D2'. How do I convert?
Our calculator provides an approximation based on component weights. Professional swing weight scales measure on the D-0 to D-9 scale (and beyond). Generally, each increment on the D-scale (e.g., D1 to D2) represents about 2.77 grams of added weight at the butt end or an equivalent shift in balance. Our results give you a good estimate to understand trends and make adjustments.
What does the 'Balance Point' input mean?
The balance point of the shaft (or club) is the point at which it would balance horizontally on a fingertip. Measuring it from the butt end tells us where the shaft's center of mass lies relative to the grip. A higher balance point (closer to the club head) means more weight is concentrated towards the head, increasing swing weight.
Can I use this for putters?
While the principles of weight distribution apply, putters are typically measured differently and often have specific weight requirements that aren't directly captured by standard swing weight calculations. This calculator is best suited for woods, hybrids, irons, and wedges.
Estimate your potential driving distance based on key swing metrics.
var chartInstance = null; // Global variable to hold chart instance
function validateInput(id, min, max, errorId, errorMessage) {
var input = document.getElementById(id);
var value = parseFloat(input.value);
var errorSpan = document.getElementById(errorId);
errorSpan.textContent = "; // Clear previous error
if (isNaN(value)) {
errorSpan.textContent = 'Please enter a valid number.';
return false;
}
if (value max) {
errorSpan.textContent = `Value cannot exceed ${max}.`;
return false;
}
return true;
}
function calculateSwingWeight() {
var isValid = true;
isValid &= validateInput('clubHeadWeight', 100, 500, 'clubHeadWeightError', 'Club head weight must be between 100g and 500g.');
isValid &= validateInput('shaftWeight', 20, 100, 'shaftWeightError', 'Shaft weight must be between 20g and 100g.');
isValid &= validateInput('gripWeight', 10, 100, 'gripWeightError', 'Grip weight must be between 10g and 100g.');
isValid &= validateInput('totalClubLength', 30, 50, 'totalClubLengthError', 'Total club length must be between 30in and 50in.');
isValid &= validateInput('balancePoint', 15, 30, 'balancePointError', 'Balance point must be between 15in and 30in.');
if (!isValid) {
document.getElementById('results-container').style.display = 'none';
document.getElementById('chartContainer').style.display = 'none';
document.getElementById('swingWeightTable').style.display = 'none';
return;
}
var clubHeadWeight = parseFloat(document.getElementById('clubHeadWeight').value);
var shaftWeight = parseFloat(document.getElementById('shaftWeight').value);
var gripWeight = parseFloat(document.getElementById('gripWeight').value);
var totalClubLength = parseFloat(document.getElementById('totalClubLength').value);
var balancePoint = parseFloat(document.getElementById('balancePoint').value);
var totalClubWeight = clubHeadWeight + shaftWeight + gripWeight;
// This formula is a common approximation for educational purposes.
// Professional tools use more precise methods or direct measurement.
// The formula aims to quantify the torque generated by the head.
// We'll use a common approximation: SW ~ (Head_Weight – Weight_of_Shaft_and_Grip_from_Butt_to_BP) * Constant
// A simpler, often-used proxy:
var weightDistributionFactor = (totalClubLength – balancePoint); // Inches of shaft beyond balance point
var effectiveWeightPerInch = (shaftWeight + gripWeight) / totalClubLength; // Average weight per inch of shaft+grip
var componentWeightContribution = clubHeadWeight – (weightDistributionFactor * effectiveWeightPerInch);
// Convert to approximate D-scale. This is a simplification.
// D0 is roughly equivalent to 400 in the context of this calculation.
// Each D increment is ~2.77g effective weight.
var approximateSwingWeightValue = (componentWeightContribution – 400) * 100; // This scaling might need adjustment based on standard scales
// Simplified calculation proxy for display, often mapped to D-scale manually or via scale
// Let's use a common club fitting calculation approach:
// Weight of shaft + grip past the balance point
var weightPastBP = (shaftWeight + gripWeight) * ( (totalClubLength – balancePoint) / totalClubLength );
var swingWeightApprox = clubHeadWeight – weightPastBP; // This value is not directly D-scale but reflects balance
// Let's use the common proxy related to component weight difference
var weightDifference = clubHeadWeight – (shaftWeight + gripWeight); // Simplified difference
// A commonly cited formula related to torque:
// SW_Torque = (Club_Head_Weight – (Total_Club_Length – Balance_Point) * (Shaft_Weight + Grip_Weight) / Total_Club_Length) * 100
// This is still an approximation. For practical D-scale, direct measurement is best.
// Let's adapt the formula from the explanation for internal use:
var weightPerInchOfShaft = (shaftWeight + gripWeight) / totalClubLength;
var estimatedTorqueFactor = clubHeadWeight – ( (totalClubLength – balancePoint) * weightPerInchOfShaft );
// To map this to D-scale, we need a reference. Let's assume a standard D0 is around 390-400 "effective head weight" relative to shaft/grip distribution.
// Each unit increase in this factor (estimatedTorqueFactor) corresponds to roughly 100 "points" on the D-scale (D0 = 400, D1 = 410, etc.)
var dScaleValue = estimatedTorqueFactor; // Raw value
// Convert to D-scale representation (e.g., D0, D1, etc.)
var swingWeightLetter = 'D';
var swingWeightNumber = 0;
var referencePoint = 400; // Approximate reference for D0
if (dScaleValue > referencePoint) {
swingWeightNumber = Math.round((dScaleValue – referencePoint) / 10); // Each point is ~10 for D-scale approx
if (swingWeightNumber >= 10) {
swingWeightLetter = String.fromCharCode(swingWeightLetter.charCodeAt(0) + Math.floor(swingWeightNumber / 10));
swingWeightNumber = swingWeightNumber % 10;
}
} else if (dScaleValue = 10) {
var numLetters = Math.ceil(numIncrements / 10);
swingWeightLetter = String.fromCharCode(swingWeightLetter.charCodeAt(0) – numLetters);
swingWeightNumber = 10 – (numIncrements % 10);
if (swingWeightNumber === 10) swingWeightNumber = 0; // Handle cases like C9
} else {
swingWeightNumber = 10 – numIncrements;
if (swingWeightNumber === 10) { // Handle C9 case
swingWeightLetter = 'C';
swingWeightNumber = 9;
} else {
swingWeightLetter = 'D';
}
}
if (swingWeightNumber < 0) swingWeightNumber = 0; // Cap at C0 if very light
if (swingWeightLetter < 'A') swingWeightLetter = 'A'; // Cap at A
}
// Ensure standard D-scale values are within reasonable bounds.
if (dScaleValue < 300) { // Below C0
swingWeightLetter = 'A'; swingWeightNumber = 0;
} else if (dScaleValue 9) { swingWeightLetter = 'D'; swingWeightNumber = 0;} // Cap at C9
} else { // D scale and above
var dScaleValueAdj = dScaleValue;
swingWeightLetter = 'D';
swingWeightNumber = Math.round((dScaleValueAdj – 400) / 10);
if (swingWeightNumber >= 10) {
var extraLetters = Math.floor(swingWeightNumber / 10);
swingWeightLetter = String.fromCharCode(swingWeightLetter.charCodeAt(0) + extraLetters);
swingWeightNumber = swingWeightNumber % 10;
}
if (swingWeightLetter > 'G') swingWeightLetter = 'G'; // Cap at G
}
var finalSwingWeight = swingWeightLetter + swingWeightNumber;
var componentWeightContributionValue = estimatedTorqueFactor; // This is the raw value used for calculation
var shaftMomentOfInertiaProxy = (shaftWeight + gripWeight); // Simplified proxy
var balancePointContributionValue = (totalClubLength – balancePoint) * weightPerInchOfShaft; // Weight of components past BP
document.getElementById('primaryResult').textContent = finalSwingWeight;
document.getElementById('componentWeightContribution').textContent = componentWeightContributionValue.toFixed(2);
document.getElementById('shaftMomentOfInertiaProxy').textContent = shaftMomentOfInertiaProxy.toFixed(2) + " g";
document.getElementById('balancePointContribution').textContent = balancePointContributionValue.toFixed(2) + " g";
document.getElementById('results-container').style.display = 'block';
document.getElementById('chartContainer').style.display = 'block';
document.getElementById('swingWeightTable').style.display = 'table';
// Update table
document.getElementById('tableClubHeadWeight').textContent = clubHeadWeight.toFixed(2);
document.getElementById('tableShaftWeight').textContent = shaftWeight.toFixed(2);
document.getElementById('tableGripWeight').textContent = gripWeight.toFixed(2);
document.getElementById('tableTotalWeight').textContent = totalClubWeight.toFixed(2);
document.getElementById('tableSwingWeight').textContent = finalSwingWeight;
// Approximate contributions for table (these are conceptual, not direct formula outputs)
var theoreticalHeadContrib = clubHeadWeight; // Head weight itself
var theoreticalShaftContrib = shaftWeight * (balancePoint / totalClubLength); // Portion of shaft weight before BP
var theoreticalGripContrib = gripWeight * (balancePoint / totalClubLength); // Portion of grip weight before BP
document.getElementById('tableClubHeadContribution').textContent = theoreticalHeadContrib.toFixed(2) + "g";
document.getElementById('tableShaftContribution').textContent = theoreticalShaftContrib.toFixed(2) + "g";
document.getElementById('tableGripContribution').textContent = theoreticalGripContrib.toFixed(2) + "g";
// Update Chart
updateChart(clubHeadWeight, shaftWeight, gripWeight, finalSwingWeight);
}
function updateChart(headW, shaftW, gripW, sw) {
var ctx = document.getElementById('swingWeightChart').getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
// Chart data: Weights vs. Swing Weight
var labels = ['Club Head Weight', 'Shaft Weight', 'Grip Weight'];
var weights = [headW, shaftW, gripW];
var dataForSW = [parseFloat(sw.substring(1)), parseFloat(sw.substring(1)), parseFloat(sw.substring(1))]; // Simple representation
// Scale weights for better visual comparison if needed, or use raw values
// For this example, let's show raw weights and then a line for the SW target
var datasets = [
{
label: 'Component Weights (g)',
data: weights,
backgroundColor: 'rgba(0, 74, 153, 0.5)',
borderColor: 'var(–primary-color)',
borderWidth: 1,
type: 'bar' // Make weights bars
},
{
label: 'Swing Weight Value (approx)',
data: [0, 0, 0], // Placeholder, will align with bars if needed
pointRadius: 7,
pointBackgroundColor: 'var(–success-color)',
borderColor: 'var(–success-color)',
borderWidth: 2,
type: 'line', // Make SW a line
fill: false,
// To align SW value, we need to map it conceptually.
// Let's assume the D-scale number is the Y-value for the line.
// We need a way to represent the SW value relationally.
// Let's use the calculated number from the D-scale for plotting.
// Example: D2 = 2. Need to map this to the scale.
// For simplicity, let's assume a reference point and plot the 'target'
// If SW is D2, the numerical part is 2. We can plot this conceptually.
// Let's re-plot data based on the D-scale number
}
];
// Re-calculate chart data based on D-scale number
var swNumber = 0;
var swLetter = sw.charAt(0);
if (sw.length > 1) {
swNumber = parseInt(sw.substring(1));
}
var chartSWValue = swNumber; // Use the number part of D-scale
// For a better visual, let's plot the components against a conceptual "target balance" derived from SW.
// A common approach: Plot component weights, and then a "target" line.
// The D-scale number itself is often the target.
// Let's create a single line dataset for the calculated D-scale number value.
datasets[1].data = [chartSWValue, chartSWValue, chartSWValue]; // Repeat the SW number for each component for alignment
datasets[1].label = 'Target Swing Weight (D' + swNumber + ')';
// Need to ensure canvas is cleared and resized properly.
// Re-creating the canvas element or clearing it might be necessary.
// For simplicity with native canvas, let's just update the existing one.
// If canvas element doesn't exist or context is lost, recreate.
// This part is tricky with pure JS and single HTML.
// A better approach is to ensure the canvas is always present and sized.
// Resizing the canvas element might be needed via JS if container resizes.
// For now, assume fixed size or responsive CSS handles it.
chartInstance = new Chart(ctx, {
type: 'bar', // Default type
data: {
labels: labels,
datasets: datasets
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Weight (grams) / Swing Weight Number'
}
},
x: {
title: {
display: true,
text: 'Club Component'
}
}
},
plugins: {
title: {
display: true,
text: 'Component Weights vs. Target Swing Weight Value'
},
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.parsed.y !== null) {
if (context.dataset.label.includes('Weight')) {
label += context.parsed.y.toFixed(2) + 'g';
} else {
label += 'D' + context.parsed.y; // Display D-scale number
}
}
return label;
}
}
}
}
}
});
}
function resetCalculator() {
document.getElementById('clubHeadWeight').value = "200";
document.getElementById('shaftWeight').value = "60";
document.getElementById('gripWeight').value = "50";
document.getElementById('totalClubLength').value = "45";
document.getElementById('balancePoint').value = "22.5";
// Clear errors
document.getElementById('clubHeadWeightError').textContent = ";
document.getElementById('shaftWeightError').textContent = ";
document.getElementById('gripWeightError').textContent = ";
document.getElementById('totalClubLengthError').textContent = ";
document.getElementById('balancePointError').textContent = ";
document.getElementById('results-container').style.display = 'none';
document.getElementById('chartContainer').style.display = 'none';
document.getElementById('swingWeightTable').style.display = 'none';
if (chartInstance) {
chartInstance.destroy(); // Destroy chart on reset
chartInstance = null;
}
}
function copyResults() {
var primaryResult = document.getElementById('primaryResult').textContent;
var componentWeightContribution = document.getElementById('componentWeightContribution').textContent;
var shaftMomentOfInertiaProxy = document.getElementById('shaftMomentOfInertiaProxy').textContent;
var balancePointContribution = document.getElementById('balancePointContribution').textContent;
var tableClubHeadWeight = document.getElementById('tableClubHeadWeight').textContent;
var tableShaftWeight = document.getElementById('tableShaftWeight').textContent;
var tableGripWeight = document.getElementById('tableGripWeight').textContent;
var tableTotalWeight = document.getElementById('tableTotalWeight').textContent;
var tableSwingWeight = document.getElementById('tableSwingWeight').textContent;
var copyText = "Swing Weight Calculator Results:\n\n";
copyText += "Primary Result: " + primaryResult + "\n";
copyText += "Component Weight Contribution: " + componentWeightContribution + "\n";
copyText += "Shaft Moment of Inertia Proxy: " + shaftMomentOfInertiaProxy + "\n";
copyText += "Balance Point Contribution: " + balancePointContribution + "\n\n";
copyText += "Component Analysis:\n";
copyText += "Club Head Weight: " + tableClubHeadWeight + " g\n";
copyText += "Shaft Weight: " + tableShaftWeight + " g\n";
copyText += "Grip Weight: " + tableGripWeight + " g\n";
copyText += "Total Club Weight: " + tableTotalWeight + " g\n";
copyText += "Calculated Swing Weight: " + tableSwingWeight + "\n\n";
copyText += "Key Assumptions:\n";
copyText += "Formula used is an approximation for educational purposes.\n";
copyText += "Standard D-Scale mapping applied.\n";
var textArea = document.createElement("textarea");
textArea.value = copyText;
textArea.style.position = "fixed";
textArea.style.top = "0";
textArea.style.left = "0";
textArea.style.opacity = "0";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'Results copied!' : 'Copying failed.';
// Optional: Display a temporary message to the user
// alert(msg);
} catch (err) {
// Optional: Display error to user
// alert('Oops, unable to copy');
}
document.body.removeChild(textArea);
}
// Function to toggle FAQ answers
document.addEventListener('DOMContentLoaded', function() {
var faqQuestions = document.querySelectorAll('.faq-question');
faqQuestions.forEach(function(question) {
question.addEventListener('click', function() {
var answer = this.nextElementSibling;
if (answer.style.display === 'block') {
answer.style.display = 'none';
} else {
answer.style.display = 'block';
}
});
});
// Initial calculation on page load if defaults are set
calculateSwingWeight();
});
// Initialize Chart.js if available (assuming it's loaded externally or included)
// For a self-contained HTML, we need to include Chart.js or use native canvas drawing.
// Since the requirement is NO external libraries, Chart.js cannot be used.
// We need to replace Chart.js with native canvas drawing.
// *** NATIVE CANVAS DRAWING REPLACEMENT FOR CHART.JS ***
// This is a significant change. Instead of Chart.js, we will draw directly on the canvas.
// The following code will draw a simple bar chart and a line.
function drawNativeChart(ctx, headW, shaftW, gripW, sw) {
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Clear canvas
var chartAreaWidth = ctx.canvas.width – 100; // Leave space for labels
var chartAreaHeight = ctx.canvas.height – 80; // Leave space for titles/labels
var labels = ['Club Head', 'Shaft', 'Grip'];
var weights = [headW, shaftW, gripW];
var swNumber = 0;
var swLetter = sw.charAt(0);
if (sw.length > 1) {
swNumber = parseInt(sw.substring(1));
}
var chartSWValue = swNumber; // Use the number part of D-scale
// Determine max value for scaling
var maxWeight = Math.max.apply(null, weights);
var maxValue = Math.max(maxWeight, chartSWValue) * 1.1; // Add 10% buffer
// Draw X-axis labels
ctx.fillStyle = '#333′;
ctx.font = '14px sans-serif';
var barWidth = chartAreaWidth / (labels.length * 2); // Width of each bar
var barSpacing = barWidth * 0.5; // Space between bars
var groupWidth = labels.length * (barWidth + barSpacing) – barSpacing;
var startX = (chartAreaWidth – groupWidth) / 2 + 50; // Center the groups
for (var i = 0; i < labels.length; i++) {
var xPos = startX + i * (barWidth + barSpacing);
ctx.fillText(labels[i], xPos + barWidth / 2, ctx.canvas.height – 20); // Draw label centered below bar
}
// Draw Y-axis labels and line
ctx.strokeStyle = '#ccc';
ctx.lineWidth = 1;
ctx.beginPath();
ctx.moveTo(50, 30); // Top of axis
ctx.lineTo(50, ctx.canvas.height – 50); // Bottom of axis
ctx.stroke();
var numYLabels = 5;
for (var i = 0; i <= numYLabels; i++) {
var yPos = ctx.canvas.height – 50 – (i * (chartAreaHeight / numYLabels));
var yValue = Math.round((i * maxValue) / numYLabels);
ctx.fillStyle = '#333';
ctx.textAlign = 'right';
ctx.fillText(yValue.toFixed(0), 45, yPos + 5);
ctx.textAlign = 'center';
ctx.fillText(yValue.toFixed(0), 50, yPos + 5); // Draw label at axis
ctx.fillStyle = '#eee'; // Light grid line
ctx.beginPath();
ctx.moveTo(50, yPos);
ctx.lineTo(ctx.canvas.width – 50, yPos);
ctx.stroke();
}
// Draw Bars (Component Weights)
ctx.fillStyle = 'rgba(0, 74, 153, 0.5)';
for (var i = 0; i < weights.length; i++) {
var barHeight = (weights[i] / maxValue) * chartAreaHeight;
var xPos = startX + i * (barWidth + barSpacing);
ctx.fillRect(xPos, ctx.canvas.height – 50 – barHeight, barWidth, barHeight);
}
// Draw Line (Swing Weight Value)
ctx.fillStyle = '#28a745'; // Success color
ctx.strokeStyle = '#28a745';
ctx.lineWidth = 2;
var xPosSW = startX + (barWidth + barSpacing) * 1.5; // Center line conceptually between bars
var yPosSW = ctx.canvas.height – 50 – (chartSWValue / maxValue) * chartAreaHeight;
ctx.beginPath();
ctx.moveTo(50, yPosSW); // Start from left edge of chart area
ctx.lineTo(ctx.canvas.width – 50, yPosSW); // End at right edge of chart area
ctx.stroke();
// Draw point for SW value
ctx.beginPath();
ctx.arc(xPosSW, yPosSW, 7, 0, Math.PI * 2);
ctx.fill();
// Draw legend/labels
ctx.textAlign = 'left';
ctx.font = '14px sans-serif';
ctx.fillStyle = '#333';
ctx.fillText('Component Weights (g)', 70, 30);
ctx.fillStyle = '#28a745';
ctx.fillText('Target Swing Weight Value (D' + swNumber + ')', 70, 50);
}
// Override updateChart to use native drawing
function updateChart(headW, shaftW, gripW, sw) {
var canvas = document.getElementById('swingWeightChart');
if (!canvas) return; // Canvas not found
// Ensure canvas has dimensions set if not in HTML
canvas.width = canvas.clientWidth || 600;
canvas.height = canvas.clientHeight || 300;
var ctx = canvas.getContext('2d');
if (!ctx) return; // Context not available
drawNativeChart(ctx, headW, shaftW, gripW, sw);
}