Density of the material (e.g., steel ~7.85 g/cm³ or 0.283 lb/in³). Ensure units are consistent.
Outer diameter of the coil in your chosen unit (mm, cm, inches).
Inner diameter of the coil in the same unit as OD.
Width of the coil in the same unit as diameters.
g/cm³
kg/m³
lb/in³
lb/ft³
Select the unit corresponding to your material density input.
mm
cm
m
inches
feet
Select the unit for Outer Diameter, Inner Diameter, and Coil Width.
Calculation Results
Volume: N/A
Mass per Unit Length: N/A
Total Coil Length: N/A
N/A
The coil weight is calculated by determining the volume of the material in the coil and then multiplying it by the material's density. This is done by treating the coil as a hollow cylinder and calculating the volume of the metal shell.
**Formula:** Weight = Volume × Density
where Volume = π/4 × (OD² – ID²) × Width
Coil Weight vs. Coil Width
This chart visualizes how the total coil weight changes with varying coil widths, assuming other parameters remain constant.
Coil Weight Calculation Variables
Variable
Meaning
Unit
Typical Range/Example
Material Density (ρ)
Mass per unit volume of the material.
Depends on unit selection (g/cm³, kg/m³, lb/in³, lb/ft³)
Steel: 7.85 g/cm³ (0.283 lb/in³)
Outer Diameter (OD)
The external diameter of the wound coil.
Depends on unit selection (mm, cm, m, in, ft)
500 mm – 2000 mm
Inner Diameter (ID)
The internal diameter of the wound coil.
Depends on unit selection (mm, cm, m, in, ft)
100 mm – 1500 mm
Coil Width (W)
The dimension of the coil perpendicular to the diameter.
Depends on unit selection (mm, cm, m, in, ft)
50 mm – 1000 mm
Volume (V)
The space occupied by the material of the coil.
Cubic units (cm³, m³, in³, ft³)
Calculated
Mass per Unit Length (M/L)
The weight of the coil per unit of its circumference at a mean radius.
Mass unit per length unit (g/mm, kg/m, lb/in, lb/ft)
Calculated
Total Coil Length (L)
The approximate total length of the material wound in the coil.
Length unit (mm, cm, m, in, ft)
Calculated
Coil Weight (M)
The total weight of the coil.
Mass unit (g, kg, lb)
Calculated
Understanding How to Calculate Coil Weight
{primary_keyword} is a fundamental calculation across many industries, particularly in manufacturing, warehousing, and logistics, where metal coils (like steel, aluminum, copper) are frequently handled. Accurate coil weight calculation is crucial for inventory management, shipping cost estimation, material yield tracking, and ensuring the structural integrity of handling equipment.
What is Coil Weight?
Coil weight refers to the total mass of a coiled material, typically a long, flat sheet or strip of metal wound around a central core. Calculating this weight involves understanding the material's properties and its physical dimensions. It's not just about the size of the coil but also the density of the substance it's made from.
Who should use it:
Metal Service Centers
Manufacturers using coiled raw materials (automotive, appliance, construction)
Logistics and Shipping Companies
Inventory Managers
Purchasing Departments
Engineers designing material handling systems
Common misconceptions:
Assuming all coils of the same dimensions weigh the same (material density varies).
Using inconsistent units across different measurements (e.g., OD in meters, density in g/cm³).
Overlooking the impact of the coil's inner diameter (core size) on the actual material volume.
Confusing weight with mass, though for practical purposes in many contexts, they are used interchangeably.
{primary_keyword} Formula and Mathematical Explanation
The core principle behind {primary_keyword} is determining the volume of the material forming the coil and multiplying it by the material's density. A coil is essentially a hollow cylinder. To find the volume of the material, we calculate the volume of the larger outer cylinder and subtract the volume of the inner (hollow) cylinder.
The formula for the volume of a cylinder is V = πr²h, where r is the radius and h is the height. In our case:
The "height" of the cylinder is the width of the coil (W).
The radius for the outer cylinder is OD/2.
The radius for the inner cylinder is ID/2.
So, the volume of the material (V) is:
V = (Volume of Outer Cylinder) – (Volume of Inner Cylinder)
V = (π * (OD/2)² * W) – (π * (ID/2)² * W)
V = π * W * [(OD/2)² – (ID/2)²]
V = π * W * [OD²/4 – ID²/4]
V = (π/4) * W * (OD² – ID²)
Once the volume (V) is calculated in cubic units (e.g., cm³), we multiply it by the material's density (ρ) in mass per cubic unit (e.g., g/cm³) to find the total weight (M):
M = V × ρ
Note on Units: It is absolutely critical that all units are consistent. If OD, ID, and W are in millimeters (mm), density should be in g/mm³ (though g/cm³ is more common, requiring conversion). If using inches, density should be in lb/in³. Our calculator handles common unit conversions to simplify this.
Variables Table:
Variable
Meaning
Unit
Typical Range/Example
Material Density (ρ)
Mass per unit volume of the material.
Depends on unit selection (g/cm³, kg/m³, lb/in³, lb/ft³)
Steel: 7.85 g/cm³ (0.283 lb/in³)
Outer Diameter (OD)
The external diameter of the wound coil.
Depends on unit selection (mm, cm, m, in, ft)
500 mm – 2000 mm
Inner Diameter (ID)
The internal diameter of the wound coil.
Depends on unit selection (mm, cm, m, in, ft)
100 mm – 1500 mm
Coil Width (W)
The dimension of the coil perpendicular to the diameter.
Depends on unit selection (mm, cm, m, in, ft)
50 mm – 1000 mm
Volume (V)
The space occupied by the material of the coil.
Cubic units (cm³, m³, in³, ft³)
Calculated
Mass per Unit Length (M/L)
The weight of the coil per unit of its circumference at a mean radius. (This is an intermediate calculation for some methods, often derived from Weight / Circumference)
Mass unit per length unit (g/mm, kg/m, lb/in, lb/ft)
Calculated
Total Coil Length (L)
The approximate total length of the material wound in the coil. (Calculated as V / (W * thickness), where thickness = (OD-ID)/2, or derived through a different approximation)
Length unit (mm, cm, m, in, ft)
Calculated
Coil Weight (M)
The total weight of the coil.
Mass unit (g, kg, lb)
Calculated
Practical Examples (Real-World Use Cases)
Example 1: Calculating the Weight of a Steel Coil
A manufacturing plant receives a steel coil. They need to know its weight for inventory records and to plan its usage.
Material: Steel
Material Density: 7.85 g/cm³
Outer Diameter (OD): 1500 mm
Inner Diameter (ID): 500 mm
Coil Width (W): 1200 mm
Units: Density in g/cm³, Dimensions in mm
Calculation Steps (using the calculator's logic):
Convert dimensions to a consistent unit for volume calculation, e.g., centimeters.
OD = 150 cm
ID = 50 cm
W = 120 cm
Calculate the volume of the material:
V = (π/4) * W * (OD² – ID²)
V = (3.14159 / 4) * 120 cm * (150² cm² – 50² cm²)
V = 0.7854 * 120 cm * (22500 cm² – 2500 cm²)
V = 94.247 cm * (20000 cm²)
V = 1,884,940 cm³
Calculate the weight using density:
M = V * ρ
M = 1,884,940 cm³ * 7.85 g/cm³
M = 14,796,789 grams
Convert grams to kilograms:
M = 14,796,789 g / 1000 g/kg = 14,796.79 kg
Result: The steel coil weighs approximately 14,796.79 kg. This allows the plant to accurately update their inventory and plan subsequent manufacturing processes.
Example 2: Estimating Aluminum Coil Weight for Shipping
A logistics manager needs to estimate the weight of an aluminum coil to determine shipping costs and container requirements.
Material: Aluminum
Material Density: 0.098 lb/in³
Outer Diameter (OD): 48 inches
Inner Diameter (ID): 20 inches
Coil Width (W): 36 inches
Units: Density in lb/in³, Dimensions in inches
Calculation Steps (using the calculator's logic):
Dimensions are already in inches, consistent with density units.
Calculate the volume of the material:
V = (π/4) * W * (OD² – ID²)
V = (3.14159 / 4) * 36 in * (48² in² – 20² in²)
V = 0.7854 * 36 in * (2304 in² – 400 in²)
V = 28.274 in * (1904 in²)
V = 53,835.7 in³
Calculate the weight using density:
M = V * ρ
M = 53,835.7 in³ * 0.098 lb/in³
M = 5,275.9 lb
Result: The aluminum coil weighs approximately 5,275.9 lb. The logistics manager can now use this figure for shipping quotes and to ensure appropriate handling equipment is used.
How to Use This Coil Weight Calculator
Our calculator simplifies the process of {primary_keyword}. Follow these steps for accurate results:
Input Material Density: Enter the density of your coil material. Ensure you know the correct unit (e.g., g/cm³, lb/in³).
Select Density Unit: Choose the unit that matches your density input from the dropdown.
Input Coil Dimensions: Enter the Outer Diameter (OD), Inner Diameter (ID), and Coil Width.
Select Dimension Unit: Choose the unit for your dimensions (mm, cm, m, inches, feet). This unit must be consistent for all three dimension inputs.
Click 'Calculate Weight': The calculator will instantly display the total coil weight, along with intermediate values like the material volume and approximate coil length.
Understand the Results: The primary result is the total weight of the coil. Intermediate values provide insight into the coil's geometry and material volume. The formula explanation clarifies the calculation logic.
Use 'Copy Results': If you need to paste the calculated values elsewhere, use this button.
Use 'Reset': To start over with default or blank fields, click 'Reset'.
Decision-Making Guidance: Use the calculated weight to verify supplier specifications, determine shipping LTL vs. FTL freight, plan crane loads, or manage raw material inventory levels. For example, if a received coil weighs significantly less than calculated, it might indicate an incorrect measurement or material specification issue.
Key Factors That Affect Coil Weight Results
Several factors influence the accuracy of your {primary_keyword} calculation. Understanding these is key to reliable results:
Material Density: This is the most critical factor. Different alloys or even batches of the same material can have slightly different densities. Always use the precise density for the material being measured. For example, the density of stainless steel differs from carbon steel.
Dimensional Accuracy (OD, ID, Width): Precise measurements of the outer diameter, inner diameter, and width are essential. Small errors in measurement, especially in diameter, can lead to significant variations in calculated volume and weight.
Unit Consistency: As emphasized, using the same units for all dimensions and ensuring they match the density units is paramount. Mixing cm with inches or kg/m³ with lb/in³ will yield incorrect results.
Coil Uniformity: This calculation assumes a perfectly uniform coil (a true hollow cylinder). In reality, coils can have slight variations in width or winding tightness, which can affect the precise volume.
Core Material: The calculation provided assumes the core (the hollow center) is empty space. If the coil is wound around a solid core, the core's volume and weight would need to be subtracted. Our calculator assumes an empty core.
Material Type and Grade: Beyond basic density, the specific grade or alloy of a metal can influence its exact density and, consequently, its weight. Always refer to material specifications.
Temperature Effects: While usually negligible for most industrial applications, extreme temperature fluctuations can cause materials to expand or contract slightly, altering their density and dimensions.
Edge Trim / Slitting Width Loss: If the coil has been slit from a wider master coil, there might be minor material loss due to the cutting process. This calculator doesn't account for that specific loss.
Frequently Asked Questions (FAQ)
Q1: What is the difference between weight and mass?
A1: Mass is the amount of matter in an object, typically measured in kilograms (kg) or pounds (lb). Weight is the force of gravity acting on that mass, often measured in Newtons (N) or pounds-force (lbf). However, in common industrial and logistical contexts, "weight" is often used interchangeably with mass, and results are usually expressed in kg or lb.
Q2: Can I use this calculator for non-metal coils like plastic or paper?
A2: Yes, as long as you have the correct density for the plastic or paper material and ensure consistent units. The geometric calculation remains the same.
Q3: My coil OD is measured in meters, but density is in g/cm³. How do I handle this?
A3: You need to convert units so they are compatible. For example, convert meters to centimeters (1m = 100cm) or convert density (e.g., 1 g/cm³ = 1000 kg/m³). Our calculator has unit selectors to help manage this.
Q4: What if my coil isn't perfectly round?
A4: This calculator provides an estimate based on ideal cylindrical geometry. For highly non-uniform coils, more advanced measurement techniques or averaging methods might be needed for extreme precision.
Q5: How does the calculator estimate the total length of the coil?
A5: The total length is often derived using an approximation or by calculating the volume and dividing by the material's cross-sectional area (Width x Thickness). The thickness is derived from (OD – ID) / 2. This is an approximation, as the effective thickness changes slightly across the coil's radius.
Q6: What is a typical density for steel?
A6: For common carbon steel, the density is approximately 7.85 grams per cubic centimeter (g/cm³) or 0.283 pounds per cubic inch (lb/in³).
Q7: Does the core (mandrel) add weight?
A7: This calculator assumes the 'Inner Diameter' refers to the empty space or the diameter of the winding start, not a solid core. If your coil is wound around a specific core, you would need to calculate the core's weight separately and add it, or adjust the volume calculation if the core is part of the specified ID.
Q8: Why is knowing coil weight important for inventory?
A8: Accurate inventory weight allows for precise tracking of assets, helps prevent stockouts or overstocking, aids in insurance valuations, and ensures you know exactly how much raw material is available for production orders.
Q9: How can I find the density of a specific material?
A9: Material density can usually be found on the manufacturer's specification sheet, material safety data sheets (MSDS), or reliable engineering handbooks and online material databases. Always use the most accurate source for your specific alloy.
Useful for estimating coatings or plating needs for coiled materials.
var PI = Math.PI;
function getInputValue(id) {
var element = document.getElementById(id);
if (element) {
var value = parseFloat(element.value);
return isNaN(value) ? null : value;
}
return null;
}
function setErrorMessage(id, message) {
var errorElement = document.getElementById(id + 'Error');
if (errorElement) {
errorElement.textContent = message;
errorElement.style.display = message ? 'block' : 'none';
}
}
function clearErrorMessages() {
var errorElements = document.querySelectorAll('.error-message');
for (var i = 0; i < errorElements.length; i++) {
errorElements[i].textContent = '';
errorElements[i].style.display = 'none';
}
}
function convertUnits(value, fromUnit, toUnit) {
if (fromUnit === toUnit) return value;
var factors = {
mm: { cm: 0.1, m: 0.001, in: 1/25.4, ft: 1/(25.4*12) },
cm: { mm: 10, m: 0.01, in: 1/2.54, ft: 1/(2.54*12) },
m: { mm: 1000, cm: 100, in: 39.3701, ft: 3.28084 },
in: { mm: 25.4, cm: 2.54, m: 0.0254, ft: 1/12 },
ft: { mm: 304.8, cm: 30.48, m: 0.3048, in: 12 }
};
if (factors[fromUnit] && factors[fromUnit][toUnit]) {
return value * factors[fromUnit][toUnit];
}
// Handle density conversions (more complex due to cubic units)
var densityFactors = {
g_cm3: { kg_m3: 1000, lb_in3: 0.0000181, lb_ft3: 0.062428 },
kg_m3: { g_cm3: 0.001, lb_in3: 0.0000000181, lb_ft3: 0.062428 / 1000 * 1000 }, // Approx
lb_in3: { g_cm3: 18.1, kg_m3: 18100, lb_ft3: 1728 },
lb_ft3: { g_cm3: 0.0160185, kg_m3: 1.60185, lb_in3: 1/1728 }
};
if (densityFactors[fromUnit] && densityFactors[fromUnit][toUnit]) {
return value * densityFactors[fromUnit][toUnit];
}
// Special case for density conversion involving cubic units implicitly
if (fromUnit === 'g_cm3' && toUnit === 'kg_m3') return value * 1000;
if (fromUnit === 'kg_m3' && toUnit === 'g_cm3') return value / 1000;
if (fromUnit === 'lb_in3' && toUnit === 'lb_ft3') return value * 1728;
if (fromUnit === 'lb_ft3' && toUnit === 'lb_in3') return value / 1728;
if (fromUnit === 'g_cm3' && toUnit === 'lb_in3') return value * 0.000018109; // 1 g/cm^3 = 0.000018109 lb/in^3
if (fromUnit === 'lb_in3' && toUnit === 'g_cm3') return value / 0.000018109; // 1 lb/in^3 = 18.109 g/cm^3
return null; // Indicate conversion not possible
}
function calculateCoilWeight() {
clearErrorMessages();
var density = getInputValue('materialDensity');
var od = getInputValue('coilOuterDiameter');
var id = getInputValue('coilInnerDiameter');
var width = getInputValue('coilWidth');
var densityUnit = document.getElementById('densityUnit').value;
var dimensionUnit = document.getElementById('dimensionUnit').value;
var isValid = true;
if (density === null || isNaN(density) || density <= 0) {
setErrorMessage('materialDensity', 'Please enter a valid positive density.');
isValid = false;
}
if (od === null || isNaN(od) || od <= 0) {
setErrorMessage('coilOuterDiameter', 'Please enter a valid positive outer diameter.');
isValid = false;
}
if (id === null || isNaN(id) || id < 0) {
setErrorMessage('coilInnerDiameter', 'Please enter a valid non-negative inner diameter.');
isValid = false;
}
if (width === null || isNaN(width) || width <= 0) {
setErrorMessage('coilWidth', 'Please enter a valid positive width.');
isValid = false;
}
if (od !== null && id !== null && od <= id) {
setErrorMessage('coilOuterDiameter', 'Outer Diameter must be greater than Inner Diameter.');
setErrorMessage('coilInnerDiameter', 'Inner Diameter must be less than Outer Diameter.');
isValid = false;
}
if (!isValid) {
document.getElementById('finalCoilWeight').textContent = 'N/A';
document.getElementById('intermediateVolume').innerHTML = 'Volume: N/A';
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Length: N/A';
document.getElementById('intermediateTotalLength').innerHTML = 'Total Coil Length: N/A';
updateChart([], []);
return;
}
// — Unit Conversions —
// Convert all dimensions to a base unit for calculation, e.g., cm
var baseDimensionUnit = 'cm';
var odCm = convertUnits(od, dimensionUnit, baseDimensionUnit);
var idCm = convertUnits(id, dimensionUnit, baseDimensionUnit);
var widthCm = convertUnits(width, dimensionUnit, baseDimensionUnit);
// Convert density to a base unit for calculation, e.g., g/cm³
var baseDensityUnit = 'g_cm3';
var densityGCm3 = convertUnits(density, densityUnit, baseDensityUnit);
if (odCm === null || idCm === null || widthCm === null || densityGCm3 === null) {
console.error("Unit conversion failed. Check units and conversion logic.");
document.getElementById('finalCoilWeight').textContent = 'Error';
document.getElementById('intermediateVolume').innerHTML = 'Volume: Error';
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Length: Error';
document.getElementById('intermediateTotalLength').innerHTML = 'Total Coil Length: Error';
return;
}
// — Calculations —
// Volume in cm³
var volumeCm3 = (PI / 4) * widthCm * (Math.pow(odCm, 2) – Math.pow(idCm, 2));
// Weight in grams (since density is g/cm³)
var weightGrams = volumeCm3 * densityGCm3;
// Convert weight back to a user-friendly unit, typically kg or lb
var finalWeight = weightGrams;
var finalWeightUnit = 'g';
if (weightGrams >= 1000) {
finalWeight = weightGrams / 1000;
finalWeightUnit = 'kg';
if (finalWeight > 2.20462) { // Threshold to switch to lbs if density was originally lb/in³ or lb/ft³
// Attempt to convert final weight based on original density unit context
if (densityUnit.includes('lb')) {
finalWeight = weightGrams / 453.592; // grams to lbs
finalWeightUnit = 'lb';
} else {
finalWeightUnit = 'kg'; // Default to kg if not specifically lbs
}
}
}
// Intermediate calculation: Mass per Unit Length (example: kg per meter)
// This requires knowing the circumference at mean radius and converting units
var meanRadiusCm = (odCm + idCm) / 2;
var meanCircumferenceCm = 2 * PI * meanRadiusCm;
var massPerCm = weightGrams / (meanCircumferenceCm * widthCm / (Math.pow(widthCm, 2)/widthCm)); // A simplified approach: total mass / effective length estimate
// A more standard "Mass per Unit Length" could be kg/meter for a given width
var massPerMeter = (weightGrams / 1000) / (convertUnits(widthCm, baseDimensionUnit, 'm') * (meanCircumferenceCm / convertUnits(widthCm, baseDimensionUnit, 'm'))); // Very approximate
// Calculate approximate total length
var thicknessCm = (odCm – idCm) / 2;
var approximateLengthCm = (thicknessCm > 0) ? (volumeCm3 / (widthCm * thicknessCm)) : 0;
var approximateLength = approximateLengthCm;
var lengthUnit = 'cm';
if (approximateLength >= 100) {
approximateLength = approximateLength / 100; // to meters
lengthUnit = 'm';
if (approximateLength > 3.28084) { // If it makes sense to use feet
approximateLength = approximateLength * 3.28084;
lengthUnit = 'ft';
}
} else if (approximateLength < 1) { // If too small for cm, try mm
approximateLength = approximateLength * 10;
lengthUnit = 'mm';
}
// — Display Results —
document.getElementById('finalCoilWeight').textContent = finalWeight.toFixed(2) + ' ' + finalWeightUnit;
document.getElementById('intermediateVolume').innerHTML = 'Volume: ' + volumeCm3.toFixed(2) + ' cm³';
// Display Mass per Unit Length appropriately
var massPerUnitLengthDisplay = 'N/A';
if (meanCircumferenceCm > 0 && widthCm > 0) {
var massPerCmApprox = weightGrams / (meanCircumferenceCm * widthCm); // Mass per unit of spiral path length
if (massPerCmApprox 0 && coilWidthM > 0) {
var intermediateMassPerMeter = (weightGrams / 1000) / (meanCircumferenceM * coilWidthM); // Very rough estimate
// A better intermediate value might be simply mass per volume unit, or weight per linear meter if width is fixed.
// Let's stick to a simpler intermediate: Mass per unit length of the central axis IF thickness was uniform.
// For this formula, the simplest intermediate is often Volume. Let's refine the others.
// Refined intermediate: Mass per linear meter of coil (if width were constant 1m)
// This requires calculating the area of the cross-section and then using density.
var crossSectionalAreaCm2 = (PI/4) * (Math.pow(odCm, 2) – Math.pow(idCm, 2));
var massPerLinearCm_Width1Cm = crossSectionalAreaCm2 * densityGCm3; // g per cm length if width is 1cm
var massPerLinearM_Width1M = massPerLinearCm_Width1Cm * 10000; // Convert g/cm to kg/m (approx)
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Linear Meter (1m width): ' + (massPerLinearM_Width1M / 100).toFixed(3) + ' kg/m'; // Divide by 100 because our width is not 1m. This is still complex.
// Let's simplify: just show the volume and length as intermediates.
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Volume: ' + densityGCm3.toFixed(3) + ' g/cm³';
} else {
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Volume: ' + densityGCm3.toFixed(3) + ' g/cm³';
}
} else {
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Volume: ' + densityGCm3.toFixed(3) + ' g/cm³';
}
document.getElementById('intermediateTotalLength').innerHTML = 'Approx. Coil Length: ' + approximateLength.toFixed(2) + ' ' + lengthUnit + '';
// Update Chart
updateChart(od, width);
return true; // Indicate success
}
function resetCalculator() {
document.getElementById('materialDensity').value = '7.85';
document.getElementById('coilOuterDiameter').value = '1200';
document.getElementById('coilInnerDiameter').value = '500';
document.getElementById('coilWidth').value = '100';
document.getElementById('densityUnit').value = 'g_cm3';
document.getElementById('dimensionUnit').value = 'mm';
clearErrorMessages();
document.getElementById('finalCoilWeight').textContent = 'N/A';
document.getElementById('intermediateVolume').innerHTML = 'Volume: N/A';
document.getElementById('intermediateMassPerUnitLength').innerHTML = 'Mass per Unit Length: N/A';
document.getElementById('intermediateTotalLength').innerHTML = 'Total Coil Length: N/A';
updateChart([], []); // Clear chart
}
function copyResults() {
var resultText = "Coil Weight Calculation Results:\n\n";
resultText += "Final Coil Weight: " + document.getElementById('finalCoilWeight').textContent + "\n";
resultText += "Material Volume: " + document.getElementById('intermediateVolume').querySelector('span').textContent + "\n";
resultText += "Mass per Unit Volume: " + document.getElementById('intermediateMassPerUnitLength').querySelector('span').textContent + "\n";
resultText += "Approximate Coil Length: " + document.getElementById('intermediateTotalLength').querySelector('span').textContent + "\n\n";
resultText += "Key Assumptions:\n";
resultText += "Material Density: " + document.getElementById('materialDensity').value + " " + document.getElementById('densityUnit').options[document.getElementById('densityUnit').selectedIndex].text + "\n";
resultText += "Outer Diameter: " + document.getElementById('coilOuterDiameter').value + " " + document.getElementById('dimensionUnit').options[document.getElementById('dimensionUnit').selectedIndex].text + "\n";
resultText += "Inner Diameter: " + document.getElementById('coilInnerDiameter').value + " " + document.getElementById('dimensionUnit').options[document.getElementById('dimensionUnit').selectedIndex].text + "\n";
resultText += "Coil Width: " + document.getElementById('coilWidth').value + " " + document.getElementById('dimensionUnit').options[document.getElementById('dimensionUnit').selectedIndex].text + "\n";
try {
navigator.clipboard.writeText(resultText).then(function() {
alert("Results copied to clipboard!");
}, function(err) {
console.error('Could not copy text: ', err);
alert("Failed to copy results. Please copy manually.");
});
} catch (e) {
console.error('Clipboard API not available: ', e);
alert("Clipboard API not supported. Please copy manually.");
}
}
// — Charting —
var chartInstance = null;
var chartCanvas = document.getElementById('weightWidthChart');
function updateChart(initialOD, initialWidth) {
if (!chartCanvas) return;
// If a chart already exists, destroy it before creating a new one
if (chartInstance) {
chartInstance.destroy();
}
var ctx = chartCanvas.getContext('2d');
var dataPoints = [];
var widths = [];
var minWidth = 50; // Minimum width for chart display
var maxWidth = 1500; // Maximum width for chart display
var step = (maxWidth – minWidth) / 5; // 6 data points
// Use input values or sensible defaults if calculation wasn't run
var currentOD = getInputValue('coilOuterDiameter');
var currentDensity = getInputValue('materialDensity');
var currentDimensionUnit = document.getElementById('dimensionUnit').value;
var currentDensityUnit = document.getElementById('densityUnit').value;
// If calculation hasn't run or inputs are invalid, use defaults for chart preview
if (!currentOD || currentOD <= 0) currentOD = 1200;
if (!currentDensity || currentDensity <= 0) currentDensity = 7.85;
if (!currentDimensionUnit) currentDimensionUnit = 'mm';
if (!currentDensityUnit) currentDensityUnit = 'g_cm3';
for (var i = 0; i < 6; i++) {
var w = minWidth + i * step;
widths.push(w);
// Recalculate weight for this width
var tempOD = currentOD;
var tempID = getInputValue('coilInnerDiameter');
if (!tempID || tempID tempIDCm && tempWidthCm > 0 && tempDensityGCm3 > 0) {
var volCm3 = (PI / 4) * tempWidthCm * (Math.pow(tempODCm, 2) – Math.pow(tempIDCm, 2));
var weightGrams = volCm3 * tempDensityGCm3;
var weightKg = weightGrams / 1000;
// Convert to user's selected display unit if possible
var finalWeightDisplay = weightKg;
var displayUnit = 'kg';
if (tempDensityUnit.includes('lb')) {
finalWeightDisplay = weightGrams / 453.592; // g to lb
displayUnit = 'lb';
}
dataPoints.push({ x: w, y: finalWeightDisplay });
} else {
dataPoints.push({ x: w, y: 0 }); // Push 0 if calculation is not possible
}
}
// Determine primary unit for chart based on selected dimension unit context
var chartWeightUnit = 'kg';
if (currentDensityUnit.includes('lb')) {
chartWeightUnit = 'lb';
}
chartInstance = new Chart(ctx, {
type: 'line',
data: {
datasets: [{
label: 'Coil Weight (' + chartWeightUnit + ')',
data: dataPoints,
borderColor: 'var(–primary-color)',
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: true,
tension: 0.1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: 'Coil Width (' + currentDimensionUnit + ')'
},
min: minWidth,
max: maxWidth
},
y: {
title: {
display: true,
text: 'Coil Weight (' + chartWeightUnit + ')'
},
beginAtZero: true
}
},
plugins: {
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.parsed.y !== null) {
label += context.parsed.y.toFixed(2);
}
return label;
}
}
}
}
}
});
}
// Initial chart render on load
document.addEventListener('DOMContentLoaded', function() {
// Call calculateCoilWeight to set initial values and render chart with defaults
if (calculateCoilWeight()) {
// If calculation succeeded, updateChart was already called.
} else {
updateChart([], []); // Render empty chart if initial calc fails
}
});
// Re-calculate and update chart when inputs change
document.getElementById('coilWeightForm').addEventListener('input', function() {
calculateCoilWeight();
});
document.getElementById('coilWeightForm').addEventListener('change', function() { // For select elements
calculateCoilWeight();
});