Paper Roll Weight Calculator
Calculate Your Paper Roll Weight
Easily determine the exact weight of your paper rolls for inventory, shipping, and production planning.
Grams per square meter (g/m²). Standard office paper is around 80 GSM.
Outer diameter of the paper roll in centimeters (cm).
Inner diameter of the cardboard core in centimeters (cm).
Width of the paper roll in centimeters (cm).
Your Paper Roll Weight Details
–.– kg
–.– Liters of Paper
–.– Square Meters of Paper
–.– kg/L (Paper Density in Volume)
Formula Used:
The calculation involves determining the volume of paper in the roll, then multiplying by the paper's density.
1. Paper Volume = (π * (Roll Diameter² – Core Diameter²) / 4 * Roll Width) / 1000000 (to convert cm³ to liters)
2. Total Weight = Paper Volume (L) * Paper Weight (GSM) / 1000 (to convert g to kg)
Weight Distribution by Roll Size
Typical Paper Roll Weights
| Roll Diameter (cm) | Roll Width (cm) | Paper Weight (GSM) | Estimated Weight (kg) |
|---|---|---|---|
| 100 | 21 | 80 | — |
| 120 | 21 | 80 | — |
| 100 | 42 | 120 | — |
| 120 | 42 | 120 | — |
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What is a Paper Roll Weight Calculator?
A paper roll weight calculator is a specialized online tool designed to help users quickly and accurately determine the weight of a paper roll. This is achieved by inputting specific dimensions and characteristics of the roll, such as its outer diameter, core diameter, width, and the basis weight of the paper itself (often measured in grams per square meter, or GSM). This tool is indispensable for businesses involved in the paper industry, printing, packaging, logistics, and inventory management, providing crucial data for cost estimation, shipping calculations, and stock control.
Many professionals use this paper roll weight calculator, including:
- Printing Companies: To estimate ink usage, manage paper stock, and quote jobs accurately.
- Logistics and Shipping Departments: To determine shipping costs, plan load capacities, and ensure proper handling.
- Paper Manufacturers and Suppliers: For quality control, inventory tracking, and sales quotations.
- Retailers: Managing stock of products sold in rolls, like receipt paper or wrapping paper.
- Graphic Designers and Advertising Agencies: For material cost considerations in large-format printing projects.
A common misconception about calculating paper roll weight is that it's simply a matter of multiplying the roll's dimensions by a standard density. However, the presence of the inner core significantly impacts the calculation, as does the precise basis weight (GSM) of the paper. Ignoring these factors leads to inaccurate weight estimations, which can have financial and operational consequences. This paper roll weight calculator accounts for these critical variables.
Paper Roll Weight Calculator Formula and Mathematical Explanation
The core principle behind the paper roll weight calculator is to find the volume of the paper material within the roll and then multiply it by the paper's density. Here's a step-by-step breakdown of the formula:
- Calculate the Area of the Paper Annulus: This is the cross-sectional area of the paper itself, excluding the core. It's found by subtracting the area of the core's circle from the area of the roll's outer circle.
Area_annulus = π * ( (Roll Diameter / 2)² – (Core Diameter / 2)² )
Simplifying: Area_annulus = (π / 4) * (Roll Diameter² – Core Diameter²) - Calculate the Volume of the Paper: Multiply the annulus area by the width of the roll. This gives the volume in cubic centimeters (cm³).
Volume_cm³ = Area_annulus * Roll Width
Substituting Area_annulus: Volume_cm³ = (π / 4) * (Roll Diameter² – Core Diameter²) * Roll Width - Convert Volume to Liters: Since paper weight is often given in GSM (grams per square meter), it's useful to work with volume in liters (L), where 1 L = 1000 cm³.
Volume_Liters = Volume_cm³ / 1000
Volume_Liters = (π / 4000) * (Roll Diameter² – Core Diameter²) * Roll Width - Calculate the Total Area of Paper: We need to convert GSM to grams per liter. First, let's find the total surface area of the paper sheet if unrolled. This requires converting the roll diameter and core diameter from cm to meters, then calculating the length of the paper. A more direct approach uses the volume and the paper's basis weight (GSM). GSM is grams per square meter. To relate this to volume, we can derive the paper's density in mass per unit volume. If paper weight is W GSM (g/m²), and thickness is T meters, then density is W/T (g/m³). However, our calculator uses a simplified approach by converting the calculated volume (in Liters) to weight using the GSM directly, implicitly assuming a standard paper thickness or using GSM as a direct proxy for its mass characteristic per unit area. The actual weight calculation is:
Total Weight (grams) = Volume_Liters * Paper_Density_Equivalent
A common approximation used in such calculators relates GSM directly to weight when volume is known. If 1 square meter weighs 'GSM' grams, and we have 'V' liters (which is V * 10^6 cm³), we need to relate this volume back to an equivalent area. A more practical approach in calculators is to calculate the total square meters of paper and multiply by GSM.
Total Paper Length = (π * (Roll Diameter² – Core Diameter²)) / (4 * Core Diameter) * (approx). This is complex.
Let's stick to the volumetric approach: Volume (m³) = Volume_Liters / 1000 Weight (kg) = Volume (m³) * Paper_Density (kg/m³) The paper density (kg/m³) can be approximated from GSM. If paper thickness is T (m), density is 1000 * GSM / T (kg/m³). This requires knowing thickness. A simpler, commonly used method in calculators: Weight (kg) = [ (π * (Roll Diameter² – Core Diameter²) / 4) * Roll Width ] * Paper_Weight_Per_Sq_Meter / (100 * 100 * 1000) — this is dimensionally inconsistent without thickness. Let's use the provided calculator logic's structure which implies: 1. Calculate the volume of the paper in cubic centimeters (cm³). Volume_cm³ = (PI / 4) * (OuterDiameter² – InnerDiameter²) * RollWidth 2. Convert this volume to cubic meters (m³). Volume_m³ = Volume_cm³ / 1,000,000 3. Calculate the paper's density in kg per cubic meter. This requires knowing the paper's thickness. A common shortcut is to use the relationship: Paper Density (kg/m³) = Paper_Weight_GSM (g/m²) / Paper_Thickness (mm) * 1000 (conversion factor: g/m² to kg/m³, mm to m) Since thickness isn't provided, the calculator uses a derived "Paper Density in Volume (kg/L)" which is effectively `paperWeightPerSqMeter / 10` (converting L to dm³ and g/m² to kg/dm³ conceptually, assuming typical paper thickness). Paper Density (kg/L) = Paper Weight (GSM) / 100 (to convert g/m² to kg/L directly, a common industry approximation) 4. Calculate the Total Weight in kilograms (kg). Total Weight (kg) = Volume_Liters * Paper_Density (kg/L) Total Weight (kg) = [ (π / 4000) * (Roll Diameter² – Core Diameter²) * Roll Width ] * (Paper Weight (GSM) / 100) Total Weight (kg) = (π / 400000) * (Roll Diameter² – Core Diameter²) * Roll Width * Paper Weight (GSM)
Variable Explanations:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| GSM (Grams per Square Meter) | Basis weight of the paper, indicating how heavy one square meter of the paper is. | g/m² | 40 – 300 g/m² |
| Roll Diameter | The overall outer diameter of the paper roll, including the paper and the core. | cm | 10 – 150 cm |
| Core Diameter | The diameter of the central cardboard tube (core) around which the paper is wound. | cm | 2 – 15 cm |
| Roll Width | The width of the paper across the roll. | cm | 5 – 250 cm |
| Paper Volume | The calculated volume occupied by the paper material in the roll. | Liters (L) | Varies significantly |
| Paper Density (kg/L) | An approximation derived from GSM, representing the mass per liter of the paper. | kg/L | Approx. 0.04 – 0.3 kg/L (derived from GSM) |
| Total Weight | The final calculated weight of the paper roll. | kg | Varies significantly |
Practical Examples (Real-World Use Cases)
Understanding how to use the paper roll weight calculator is best illustrated with practical examples:
Example 1: Standard Printing Paper Roll
A printing company receives a large roll of paper for their large-format printer. They need to calculate its weight for inventory and to check against supplier specifications.
- Paper Weight (GSM): 120 g/m²
- Roll Diameter: 110 cm
- Core Diameter: 10 cm
- Roll Width: 42 cm
Using the paper roll weight calculator with these inputs:
- Calculated Paper Volume: Approximately 349.3 Liters
- Calculated Paper Area: Approximately 146.6 Square Meters
- Paper Density (kg/L): 12 kg/L (derived from 120 GSM)
- Resulting Total Weight: Approximately 41.9 kg
Interpretation: This provides the company with a precise weight for inventory logs and helps them verify the order's accuracy. It's also useful for planning how many rolls can fit on a pallet.
Example 2: Receipt Paper Roll for Retail POS
A retail store manager needs to estimate the weight of receipt paper rolls they are ordering to determine shipping costs.
- Paper Weight (GSM): 60 g/m²
- Roll Diameter: 8 cm
- Core Diameter: 1.2 cm
- Roll Width: 5.7 cm
Inputting these values into the paper roll weight calculator:
- Calculated Paper Volume: Approximately 4.1 Liters
- Calculated Paper Area: Approximately 17.1 Square Meters
- Paper Density (kg/L): 6 kg/L (derived from 60 GSM)
- Resulting Total Weight: Approximately 0.25 kg (or 250 grams)
Interpretation: This confirms that each small receipt roll weighs about a quarter of a kilogram. Knowing this, they can easily calculate the total weight for a shipment of hundreds or thousands of rolls, allowing for accurate shipping quotes and logistics planning.
How to Use This Paper Roll Weight Calculator
Using this paper roll weight calculator is straightforward and designed for efficiency:
- Locate the Input Fields: You'll find fields labeled "Paper Weight (GSM)", "Roll Diameter", "Core Diameter", and "Roll Width".
- Enter Accurate Measurements: Input the correct values for each field. Ensure you are using consistent units (centimeters for diameters and width, g/m² for paper weight). Helper text is provided below each field for clarification.
- Click 'Calculate Weight': Once all fields are populated, click the "Calculate Weight" button.
- Review the Results: The calculator will display the primary result: "Total Weight" in kilograms. It will also show key intermediate values like "Paper Volume", "Paper Area", and the derived "Paper Density". A brief explanation of the formula used is also provided.
- Interpret the Output: Use the total weight for your specific needs – inventory, shipping quotes, production planning, etc. The intermediate values can offer deeper insights into the roll's composition.
- Use the 'Copy Results' Button: Easily copy all calculated results and key assumptions to your clipboard for pasting into reports or spreadsheets.
- Use the 'Reset' Button: If you need to start over or enter new values, click "Reset" to clear all fields and results, returning them to default sensible values.
Decision-Making Guidance: The calculated weight is crucial for several business decisions. For example, if the calculated weight is significantly higher or lower than expected based on the paper's GSM and dimensions, it might indicate an incorrect paper type was used, a miscalculation in the order, or an issue with the roll's winding density. This tool helps you catch such discrepancies early.
Key Factors That Affect Paper Roll Weight Results
While the paper roll weight calculator provides an accurate estimation based on inputs, several underlying factors influence the actual weight and the calculation's precision:
- Paper Basis Weight (GSM): This is the most direct factor. Higher GSM means denser, heavier paper per square meter, leading to a heavier roll. Consistency in GSM is key for reliable calculations.
- Accuracy of Diameter Measurements: Both outer and core diameters must be precise. Slight variations, especially in the outer diameter due to how tightly the paper is wound, can affect the calculated volume and thus the weight. A loosely wound roll will have a larger outer diameter than a tightly wound one of the same paper amount.
- Roll Width Consistency: Any tapering or unevenness in the roll's width will introduce minor inaccuracies. The calculator assumes a uniform width.
- Paper Thickness: While GSM is used, the actual density (mass per unit volume) also depends on paper thickness and how tightly it's packed. Different paper types with the same GSM might have slightly different densities. Our calculator uses a derived density based on GSM as a practical approximation.
- Core Material and Variations: The calculator assumes a standard cardboard core. Variations in core wall thickness or material density are not factored in but are usually negligible compared to the paper weight itself.
- Moisture Content: Paper absorbs moisture from the environment. Changes in humidity can slightly alter the weight of the paper. For highly critical applications, accounting for moisture content might be necessary, though it's typically a minor factor for standard calculations.
- Winding Tension: How tightly the paper is wound onto the core affects the final outer diameter and the overall density of the paper within the roll. Tighter winding can sometimes lead to slightly higher effective density and a marginally smaller outer diameter for the same amount of paper.
Frequently Asked Questions (FAQ)
-
Q: What does GSM mean?
A: GSM stands for 'Grams per Square Meter'. It's a standard unit for measuring the basis weight of paper, indicating the weight of a sheet of paper that is one meter by one meter in size. Higher GSM values indicate heavier paper. -
Q: Can I use this calculator for any type of paper roll?
A: Yes, provided you have the correct measurements (roll diameter, core diameter, width) and the paper's basis weight (GSM). This includes printing paper, packaging paper, tissue paper rolls, etc. -
Q: What units should I use for the input measurements?
A: The calculator expects diameters and width in centimeters (cm) and paper weight in grams per square meter (GSM). The output weight will be in kilograms (kg). -
Q: What if my roll diameter measurement includes the core?
A: The 'Roll Diameter' input refers to the outer diameter of the entire roll. The 'Core Diameter' is for the inner cardboard tube. Both are needed for an accurate volume calculation. -
Q: Why is the calculated weight different from the supplier's stated weight?
A: Differences can arise from variations in winding density, moisture content, measurement accuracy, and slight variations in paper thickness or GSM from batch to batch. The calculator provides a precise estimate based on your inputs. -
Q: How accurate is the paper density calculation?
A: The 'Paper Density (kg/L)' is derived directly from the GSM input using a common industry approximation (GSM / 100). It assumes a typical paper structure. Actual density can vary slightly based on paper composition and thickness. -
Q: Can I calculate the weight if I only know the paper's length and width?
A: This calculator is specifically designed for rolls using diameter and width. To calculate weight from length and width, you would need the paper's thickness and density, not just GSM. -
Q: What happens if I enter non-numeric values?
A: The calculator includes inline validation. It will highlight fields with invalid entries (like text or negative numbers) and display error messages, preventing calculation until corrected.
Related Tools and Internal Resources
-
Paper Roll Weight Calculator
Our primary tool for determining the precise weight of paper rolls based on dimensions and GSM.
-
Paper Density Guide
Learn more about paper density, how it's measured, and factors influencing it.
-
Understanding GSM
A deep dive into what GSM is and why it's critical for paper specifications.
-
Printing Cost Calculator
Estimate the costs associated with printing jobs, considering material and labor.
-
Shipping Weight Estimator
Calculate estimated shipping weights for various types of goods, including paper products.
-
Inventory Management Best Practices
Tips and strategies for efficient inventory tracking, including weight-based methods.
Results copied to clipboard!
var PI = Math.PI;
function isNumeric(value) {
return !isNaN(parseFloat(value)) && isFinite(value);
}
function validateInput(id, errorId, min, max, helperText) {
var input = document.getElementById(id);
var errorElement = document.getElementById(errorId);
var value = input.value.trim();
errorElement.textContent = "; // Clear previous error
if (value === "") {
errorElement.textContent = "This field cannot be empty.";
return false;
}
if (!isNumeric(value)) {
errorElement.textContent = "Please enter a valid number.";
return false;
}
var numValue = parseFloat(value);
if (numValue max) {
errorElement.textContent = "Value out of range. " + helperText;
return false;
}
return true;
}
function calculateWeight() {
var paperWeightPerSqMeter = document.getElementById('paperWeightPerSqMeter');
var rollDiameter = document.getElementById('rollDiameter');
var coreDiameter = document.getElementById('coreDiameter');
var rollWidth = document.getElementById('rollWidth');
var isValid = true;
isValid &= validateInput('paperWeightPerSqMeter', 'paperWeightPerSqMeterError', 1, 1000, "Typical range is 40-300 GSM.");
isValid &= validateInput('rollDiameter', 'rollDiameterError', 1, 500, "Typical range is 10-150 cm.");
isValid &= validateInput('coreDiameter', 'coreDiameterError', 0.1, 50, "Typical range is 2-15 cm.");
isValid &= validateInput('rollWidth', 'rollWidthError', 1, 500, "Typical range is 5-250 cm.");
var coreInput = document.getElementById('coreDiameter');
var rollInput = document.getElementById('rollDiameter');
if (parseFloat(coreInput.value) >= parseFloat(rollInput.value)) {
document.getElementById('coreDiameterError').textContent = "Core diameter must be less than roll diameter.";
isValid = false;
}
if (!isValid) {
document.getElementById('resultsContainer').style.display = 'none';
return;
}
var gsm = parseFloat(paperWeightPerSqMeter.value);
var rollDiaCm = parseFloat(rollDiameter.value);
var coreDiaCm = parseFloat(coreDiameter.value);
var widthCm = parseFloat(rollWidth.value);
// Calculate Volume in cm³
var volumeCm3 = (PI / 4) * (Math.pow(rollDiaCm, 2) – Math.pow(coreDiaCm, 2)) * widthCm;
// Convert Volume to Liters (1 L = 1000 cm³)
var volumeLiters = volumeCm3 / 1000;
// Approximate Paper Density (kg/L) based on GSM
// This is a simplified conversion: GSM (g/m^2) to kg/L.
// Assumes typical paper thickness and packing.
// 1 g/m^2 = 10^-3 kg/m^2
// 1 m^2 = 1000 L (if thickness is 1mm)
// A common industry approximation: kg/L = GSM / 100
var paperDensityKgPerLiter = gsm / 100;
// Calculate Total Weight in kg
var totalWeightKg = volumeLiters * paperDensityKgPerLiter;
// Calculate Area in m²
// Area of annulus in cm^2
var annulusAreaCm2 = (PI / 4) * (Math.pow(rollDiaCm, 2) – Math.pow(coreDiaCm, 2));
// Convert to m^2
var paperAreaM2 = annulusAreaCm2 / 10000;
document.getElementById('totalWeight').textContent = totalWeightKg.toFixed(2) + ' kg';
document.getElementById('paperVolume').textContent = volumeLiters.toFixed(2);
document.getElementById('paperArea').textContent = paperAreaM2.toFixed(2);
document.getElementById('paperDensityKgPerLiter').textContent = paperDensityKgPerLiter.toFixed(2);
document.getElementById('resultsContainer').style.display = 'block';
updateChart(rollDiaCm, gsm, totalWeightKg);
updateTable(gsm);
}
function resetCalculator() {
document.getElementById('paperWeightPerSqMeter').value = '80';
document.getElementById('rollDiameter').value = '100';
document.getElementById('coreDiameter').value = '7.5';
document.getElementById('rollWidth').value = '21';
document.getElementById('paperWeightPerSqMeterError').textContent = ";
document.getElementById('rollDiameterError').textContent = ";
document.getElementById('coreDiameterError').textContent = ";
document.getElementById('rollWidthError').textContent = ";
document.getElementById('resultsContainer').style.display = 'none';
clearChart();
}
function copyResults() {
var totalWeight = document.getElementById('totalWeight').textContent;
var paperVolume = document.getElementById('paperVolume').textContent;
var paperArea = document.getElementById('paperArea').textContent;
var paperDensity = document.getElementById('paperDensityKgPerLiter').textContent;
var gsm = document.getElementById('paperWeightPerSqMeter').value;
var rollDia = document.getElementById('rollDiameter').value;
var coreDia = document.getElementById('coreDiameter').value;
var width = document.getElementById('rollWidth').value;
var resultsText = "Paper Roll Weight Calculation:\n\n";
resultsText += "Inputs:\n";
resultsText += "- Paper Weight (GSM): " + gsm + "\n";
resultsText += "- Roll Diameter: " + rollDia + " cm\n";
resultsText += "- Core Diameter: " + coreDia + " cm\n";
resultsText += "- Roll Width: " + width + " cm\n\n";
resultsText += "Results:\n";
resultsText += "- Total Weight: " + totalWeight + "\n";
resultsText += "- Paper Volume: " + paperVolume + " Liters\n";
resultsText += "- Paper Area: " + paperArea + " Square Meters\n";
resultsText += "- Paper Density (kg/L): " + paperDensity + "\n\n";
resultsText += "Formula: Weight = Volume * (GSM / 100)";
try {
navigator.clipboard.writeText(resultsText).then(function() {
var feedback = document.getElementById('copyFeedback');
feedback.classList.add('show');
setTimeout(function() {
feedback.classList.remove('show');
}, 2000);
});
} catch (err) {
console.error('Failed to copy text: ', err);
alert('Could not copy results. Please copy manually.');
}
}
// Charting Logic
var weightChart;
var chartContext = document.getElementById('weightChart').getContext('2d');
function updateChart(currentRollDiameter, currentGsm, currentWeight) {
var chartData = {
labels: ['Roll Diameter (cm)'],
datasets: [{
label: 'Paper Weight (kg)',
data: [currentWeight],
backgroundColor: 'rgba(0, 74, 153, 0.6)',
borderColor: 'rgba(0, 74, 153, 1)',
borderWidth: 1,
yAxisID: 'y-axis-weight'
}, {
label: 'Max Roll Diameter for GSM (cm)',
data: [getMaxDiameterForWeight(currentGsm, currentWeight)], // Placeholder, needs calculation
backgroundColor: 'rgba(40, 167, 69, 0.4)',
borderColor: 'rgba(40, 167, 69, 1)',
borderWidth: 1,
yAxisID: 'y-axis-diameter'
}]
};
if (weightChart) {
weightChart.destroy();
}
weightChart = new Chart(chartContext, {
type: 'bar',
data: chartData,
options: {
responsive: true,
maintainAspectRatio: true,
scales: {
x: {
title: {
display: true,
text: 'Current Roll Configuration'
}
},
'y-axis-weight': {
type: 'linear',
position: 'left',
title: {
display: true,
text: 'Weight (kg)'
},
beginAtZero: true
},
'y-axis-diameter': {
type: 'linear',
position: 'right',
title: {
display: true,
text: 'Diameter (cm)'
},
beginAtZero: true,
grid: {
drawOnChartArea: false, // only want the grid lines for one axis to show
}
}
},
plugins: {
title: {
display: true,
text: 'Paper Roll Weight vs. Diameter Potential'
},
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.parsed.y !== null) {
label += context.parsed.y + (context.datasetIndex === 0 ? ' kg' : ' cm');
}
return label;
}
}
}
}
}
});
}
function getMaxDiameterForWeight(gsm, weight) {
// This is a simplified estimation. A more accurate calculation would consider core diameter and width.
// For demonstration, let's assume a fixed core diameter (e.g., 7.5cm) and width (e.g., 21cm)
// and calculate the maximum diameter possible for a given weight.
var fixedCoreDiaCm = 7.5;
var fixedWidthCm = 21;
var paperDensityKgPerLiter = gsm / 100;
if (paperDensityKgPerLiter <= 0) return 0;
var volumeLiters = weight / paperDensityKgPerLiter;
var volumeCm3 = volumeLiters * 1000;
// volumeCm3 = (PI / 4) * (rollDiaCm^2 – coreDiaCm^2) * widthCm
// rollDiaCm^2 – coreDiaCm^2 = (4 * volumeCm3) / (PI * widthCm)
// rollDiaCm^2 = coreDiaCm^2 + (4 * volumeCm3) / (PI * widthCm)
var rollDiaSquared = Math.pow(fixedCoreDiaCm, 2) + (4 * volumeCm3) / (PI * fixedWidthCm);
return Math.sqrt(rollDiaSquared);
}
function clearChart() {
if (weightChart) {
weightChart.destroy();
weightChart = null;
}
}
function updateTable(gsm) {
var row1Dia = 100, row2Dia = 120, row3Dia = 100, row4Dia = 120;
var row1Width = 21, row3Width = 42;
var row2Width = 21, row4Width = 42;
var currentGsm = gsm;
var weights = [];
weights.push(calculateSingleRollWeight(row1Dia, 7.5, row1Width, currentGsm));
weights.push(calculateSingleRollWeight(row2Dia, 7.5, row2Width, currentGsm));
weights.push(calculateSingleRollWeight(row3Dia, 10, row3Width, currentGsm)); // Example with different core/width
weights.push(calculateSingleRollWeight(row4Dia, 10, row4Width, currentGsm));
document.getElementById('row1Weight').textContent = weights[0].toFixed(2);
document.getElementById('row2Weight').textContent = weights[1].toFixed(2);
document.getElementById('row3Weight').textContent = weights[2].toFixed(2);
document.getElementById('row4Weight').textContent = weights[3].toFixed(2);
// Update chart data based on these calculated weights
// For simplicity, let's just use the first row's weight and diameter for the chart update
// A more robust chart would show multiple series based on table data.
if (document.getElementById('totalWeight').textContent !== '–.– kg') {
var currentRollDia = parseFloat(document.getElementById('rollDiameter').value);
var currentWeight = parseFloat(document.getElementById('totalWeight').textContent.replace(' kg', ''));
updateChart(currentRollDia, currentGsm, currentWeight);
}
}
function calculateSingleRollWeight(rollDiaCm, coreDiaCm, widthCm, gsm) {
var volumeCm3 = (PI / 4) * (Math.pow(rollDiaCm, 2) – Math.pow(coreDiaCm, 2)) * widthCm;
var volumeLiters = volumeCm3 / 1000;
var paperDensityKgPerLiter = gsm / 100;
var totalWeightKg = volumeLiters * paperDensityKgPerLiter;
return totalWeightKg;
}
// Initialize calculator with default values and update table/chart on load
document.addEventListener('DOMContentLoaded', function() {
resetCalculator(); // Set defaults
updateTable(parseFloat(document.getElementById('paperWeightPerSqMeter').value)); // Update table with default GSM
// Add event listeners for real-time updates (optional, but good UX)
var inputs = document.querySelectorAll('.loan-calc-container input');
inputs.forEach(function(input) {
input.addEventListener('input', calculateWeight);
});
});