Online Weight Calculator for Metals
Accurately calculate the weight of metal components based on their dimensions and material density.
Metal Weight Calculator
Select Metal
Aluminum
Stainless Steel
Carbon Steel
Copper
Brass
Bronze
Titanium
Lead
Zinc
Gold
Silver
Platinum
Choose the metal from the list.
Select Shape
Rectangular Prism (Bar/Plate)
Cylinder (Rod/Tube)
Sphere
Cube
Select the geometric shape of the metal part.
Calculation Results
—
Volume: —
Density Used: —
Units: —
The weight of the metal is calculated by multiplying its volume by its density.
Formula: Weight = Volume × Density.
Weight Distribution by Volume
Comparison of total weight across different volume units for the selected metal.
What is an Online Weight Calculator for Metals?
An online weight calculator for metals is a digital tool designed to help users quickly and accurately determine the mass (weight) of a metal object based on its geometric dimensions and the specific type of metal it's made from. These calculators are invaluable for a wide range of professionals and hobbyists, including engineers, machinists, fabricators, jewelers, scrap metal dealers, and DIY enthusiasts. By inputting the shape and dimensions of the metal piece, along with selecting the correct metal alloy, the tool leverages pre-programmed density values to compute the total weight. This avoids tedious manual calculations and reduces the chance of errors, which can be costly in material procurement, manufacturing, and project planning.
Who Should Use It?
- Engineers & Designers: To estimate material requirements, calculate structural loads, and optimize designs for weight efficiency.
- Fabricators & Manufacturers: For accurate material quoting, inventory management, and production planning.
- Purchasing Agents: To determine the exact quantity of metal needed, ensuring cost-effectiveness.
- Machinists: To understand the weight of workpieces for handling and machine setup.
- Jewelers & Gemologists: For precise calculation of precious metal weights, crucial for valuation.
- Scrap Metal Recyclers: To quickly assess the value of collected metal based on weight.
- Hobbyists & DIYers: For smaller projects where material cost and estimation are important.
Common Misconceptions
- Density is Constant: While standard densities are used, slight variations can occur due to manufacturing processes, impurities, or specific alloy compositions.
- Weight = Volume: This is incorrect; weight is volume multiplied by density. A large volume of a light metal (like aluminum) can weigh less than a small volume of a heavy metal (like lead).
- All Steels/Alloys are the Same: Different alloys of steel (e.g., carbon vs. stainless) or other metals have distinct densities, leading to different weights for the same dimensions.
Metal Weight Calculator Formula and Mathematical Explanation
The core principle behind calculating the weight of any object, including metals, is the relationship between its Volume, Density, and resulting Mass (Weight).
Step-by-Step Derivation:
- Determine the Volume (V): First, the geometric shape and its dimensions (length, width, height, diameter, radius) are used to calculate the object's volume. The specific formula depends on the shape.
- Identify the Density (ρ): The density of the chosen metal is retrieved from a database or standard reference values. Density is a measure of mass per unit volume.
- Calculate the Mass (Weight, W): The mass is found by multiplying the volume by the density.
Formula:
Weight (Mass) = Volume × Density
W = V × ρ
Variable Explanations:
- W (Weight/Mass): The total mass of the metal object.
- V (Volume): The space occupied by the metal object.
- ρ (Density): The intrinsic property of the material, representing how much mass is contained within a given volume.
Variables Table:
| Variable | Meaning | Unit | Typical Range (for this calculator) |
|---|---|---|---|
| Metal Type | The specific alloy of metal being used. | N/A | Aluminum, Steel, Copper, etc. |
| Shape | The geometric form of the metal part. | N/A | Rectangular Prism, Cylinder, Sphere, Cube |
| Length (L) | One dimension of the shape (e.g., length of a bar, height of a cylinder). | mm, cm, m, in, ft | 0.1 – 10000 mm (or equivalent) |
| Width (W) | Second dimension for rectangular shapes. | mm, cm, m, in, ft | 0.1 – 10000 mm (or equivalent) |
| Height (H) | Third dimension for rectangular shapes, or can be diameter for cylinder. | mm, cm, m, in, ft | 0.1 – 10000 mm (or equivalent) |
| Diameter (D) | Diameter for cylindrical or spherical shapes. | mm, cm, m, in, ft | 0.1 – 10000 mm (or equivalent) |
| Radius (R) | Radius for cylindrical or spherical shapes. | mm, cm, m, in, ft | 0.05 – 5000 mm (or equivalent) |
| Density (ρ) | Mass per unit volume of the selected metal. | kg/m³, g/cm³, lb/in³ | Varies by metal (e.g., 2.7 g/cm³ for Aluminum to 19.3 g/cm³ for Gold) |
| Volume (V) | Calculated space occupied by the metal. | mm³, cm³, m³, in³, ft³ | Calculated based on dimensions. |
| Weight (W) | The final calculated mass of the metal. | kg, g, lb, tonne | Calculated based on V and ρ. |
Practical Examples (Real-World Use Cases)
Example 1: Calculating the Weight of an Aluminum Plate
Scenario: A fabrication workshop needs to order a specific size of aluminum plate for a project. They need to know its weight to arrange for handling and transportation.
Inputs:
- Metal Type: Aluminum
- Shape: Rectangular Prism (Plate)
- Length: 1200 mm
- Width: 600 mm
- Height (Thickness): 10 mm
Calculation:
- Volume: V = Length × Width × Height = 1200 mm × 600 mm × 10 mm = 7,200,000 mm³
- Density: Standard density for Aluminum ≈ 2.7 g/cm³ (or 2700 kg/m³ or 0.0975 lb/in³). The calculator will use the appropriate conversion. Let's assume internal calculations are in g/cm³ and convert mm³ to cm³: 7,200,000 mm³ = 7200 cm³.
- Weight: W = Volume × Density = 7200 cm³ × 2.7 g/cm³ = 19440 g
Calculator Output:
- Volume: 7,200,000 mm³ (or 7200 cm³)
- Density Used: 2.7 g/cm³
- Weight: 19.44 kg
Interpretation: The aluminum plate weighs approximately 19.44 kilograms. This information is crucial for ordering the correct material and planning logistics.
Example 2: Determining the Weight of a Copper Rod
Scenario: An electrical engineer needs to determine the weight of a solid copper rod used as a busbar. This might be relevant for structural support calculations or overall system weight estimation.
Inputs:
- Metal Type: Copper
- Shape: Cylinder (Rod)
- Diameter: 2 inches
- Length: 5 feet
Calculation:
- Convert Units: Ensure consistent units. Let's convert to inches: Length = 5 feet × 12 inches/foot = 60 inches. Diameter = 2 inches, so Radius (R) = 1 inch.
- Volume: V = π × R² × Length = π × (1 inch)² × 60 inches ≈ 188.5 cubic inches (in³)
- Density: Standard density for Copper ≈ 0.323 lb/in³
- Weight: W = Volume × Density = 188.5 in³ × 0.323 lb/in³ ≈ 60.9 lb
Calculator Output:
- Volume: ≈ 188.5 in³
- Density Used: 0.323 lb/in³
- Weight: ≈ 60.9 lb
Interpretation: The copper rod weighs approximately 60.9 pounds. This value is useful for engineers assessing the physical constraints and load-bearing requirements of the electrical system.
How to Use This Online Weight Calculator for Metals
Using the online weight calculator for metals is straightforward. Follow these simple steps to get your accurate weight calculation:
- Select Metal Type: From the 'Metal Type' dropdown, choose the specific metal alloy you are working with (e.g., Aluminum, Stainless Steel, Copper). Using the correct metal is crucial as densities vary significantly.
- Choose the Shape: Select the geometric shape of your metal component from the 'Shape' dropdown (e.g., Rectangular Prism, Cylinder, Sphere, Cube).
- Enter Dimensions: Based on the selected shape, specific input fields will appear. Enter the required dimensions (e.g., Length, Width, Height, Diameter, Radius). Ensure you are using consistent units (e.g., all in millimeters or all in inches). The calculator will handle unit conversions internally for density and output, but your input dimensions should be uniform.
- Click 'Calculate Weight': Once all dimensions are entered, click the 'Calculate Weight' button.
How to Read Results:
- Main Highlighted Result: This is the primary output – the total calculated weight (mass) of the metal, displayed prominently.
- Volume: The calculated volume of the metal based on the dimensions provided.
- Density Used: Shows the specific density value for the selected metal that was used in the calculation. This helps verify accuracy.
- Units: Indicates the units used for the weight and volume output (e.g., kg, tonnes, lb, m³, cm³).
Decision-Making Guidance:
The results from this calculator can inform several critical decisions:
- Material Procurement: Order the exact amount of metal needed, minimizing waste and cost.
- Logistics & Handling: Plan for the necessary equipment (forklifts, cranes) and personnel required to move the metal.
- Cost Estimation: Use the weight to calculate the material cost for quotes and project budgets.
- Design Optimization: Compare the weights of different material choices or shapes to achieve desired performance with minimal weight.
Use the 'Copy Results' button to easily transfer the key figures to your documents or spreadsheets. The 'Reset' button allows you to quickly start a new calculation.
Key Factors That Affect Metal Weight Calculator Results
While the calculator uses standard formulas, several real-world factors can influence the actual weight of a metal component:
- Alloy Variations: The 'Metal Type' selected is often a category (e.g., 'Stainless Steel'). Different grades (e.g., 304, 316, 410) have slightly different densities due to variations in their elemental composition. For critical applications, knowing the exact grade is important.
- Manufacturing Tolerances: Real-world parts are rarely perfect. Slight deviations in dimensions (length, width, diameter) due to machining or casting tolerances will lead to minor variations in actual volume and thus weight.
- Hollow Sections vs. Solid: If calculating the weight of a tube or pipe, ensure you specify the correct inner and outer diameters or wall thickness. Mistaking a hollow shape for a solid one will result in a significantly overestimated weight. This calculator assumes solid shapes unless specifically designed for tubes (e.g., via outer diameter and wall thickness inputs if added).
- Density Fluctuations: While generally stable, a metal's density can subtly change with temperature. High temperatures can cause expansion, slightly reducing density and thus weight per unit volume. This effect is usually negligible for standard calculations but can matter in extreme environments.
- Surface Treatments & Coatings: Plating, galvanizing, or painting adds a small amount of weight. For very precise weight calculations, especially for small components like jewelry, this can be a factor, though it's often insignificant for larger structural parts.
- Impurities and Porosity: Trace impurities or internal voids (porosity) within the metal can reduce its overall effective density compared to the standard value, leading to a slightly lower actual weight. Quality control during manufacturing helps minimize this.
Frequently Asked Questions (FAQ)
Q1: What is the difference between weight and mass?
Technically, mass is the amount of matter in an object, while weight is the force of gravity on that mass. However, in common usage and for practical purposes in engineering and trade, 'weight' often refers to mass, and units like kilograms (kg) or pounds (lb) are used for both. This calculator outputs mass.
Q2: Can I calculate the weight of a custom or irregular shape?
This specific calculator is designed for standard geometric shapes (rectangular prism, cylinder, sphere, cube). For irregular shapes, you would typically need to break them down into simpler geometric components, calculate the volume of each, sum them up, and then multiply by the density. Alternatively, methods like water displacement can measure volume directly.
Q3: Why are there different densities for the same metal type (e.g., Steel)?
Metals like steel are alloys, meaning they are mixtures of elements. Different proportions of elements like carbon, chromium, nickel, etc., create different grades or types of steel (e.g., Stainless Steel 304 vs. 316, Carbon Steel). These compositional differences affect the density and other properties.
Q4: What units of measurement does the calculator accept and output?
The calculator is designed to be flexible. You can input dimensions in millimeters (mm), centimeters (cm), meters (m), inches (in), or feet (ft). The output units (e.g., kg, tonnes, lb) will be displayed alongside the results. Density is typically handled internally based on standard values, often derived from kg/m³ or g/cm³.
Q5: Does the calculator account for material waste during fabrication?
No, this calculator determines the theoretical weight of the final specified geometry. It does not account for material lost due to cutting, machining, or other fabrication processes. You may need to order slightly more material than calculated to account for waste.
Q6: How accurate are the density values used?
The calculator uses generally accepted standard density values for common metals. These are accurate for most practical purposes. However, for highly specialized or critical applications, consult the specific material data sheet (MDS) provided by the metal supplier for the most precise density value.
Q7: Can I calculate the weight of alloys not listed?
Currently, the calculator includes a curated list of common metals and alloys. If you need to calculate the weight for a less common alloy, you would need to find its specific density value and use the fundamental formula: Weight = Volume × Density.
Q8: What is the role of the chart?
The chart provides a visual comparison of how different volumes of the selected metal contribute to its overall weight. It helps to understand the direct proportionality between volume and weight for a given material. It's useful for visualizing scale and impact.
Related Tools and Internal Resources
Explore these related tools and resources to enhance your material calculations and project planning:
- Metal Properties Database: A comprehensive resource detailing the physical and mechanical properties of various metals, including density, melting point, and strength.
- Sheet Metal Thickness Calculator: Useful for determining the weight and material cost of sheet metal based on gauge and dimensions.
- Understanding Metal Alloys Guide: Learn about the composition and characteristics of different metal alloys like steel, aluminum, and brass.
- Surface Area Calculator: Calculate the surface area of various shapes, which is important for tasks like calculating paint or coating requirements.
- Cost Optimization in Manufacturing: Tips and strategies for reducing material costs and improving efficiency in production processes.
- Unit Conversion Tool: Quickly convert between different measurement units (e.g., mm to inches, kg to lbs) for materials and dimensions.
Enter the length of the object.
';
html += 'Enter the width of the object.
';
if (shape === "rectangular_prism") {
html += 'Enter the height or thickness.
';
} else { // Cube
html += 'Enter the side length (all sides are equal).
';
}
} else if (shape === "cylinder") {
html += 'Enter the diameter of the cylinder.
';
html += 'Enter the length of the cylinder.
';
} else if (shape === "sphere") {
html += 'Enter the diameter of the sphere.
';
}
shapeInputsDiv.innerHTML = html;
updateSelectedMetalDensity(); // Update density based on initial metal selection
calculateWeight(); // Recalculate immediately after inputs are updated
}
function validateInput(input, min, max) {
var value = parseFloat(input.value);
var errorDivId = input.id + "Error";
var errorDiv = document.getElementById(errorDivId);
errorDiv.textContent = "; // Clear previous error
if (isNaN(value)) {
errorDiv.textContent = "Please enter a valid number.";
input.style.borderColor = 'red';
return false;
}
if (value <= 0) {
errorDiv.textContent = "Value must be positive.";
input.style.borderColor = 'red';
return false;
}
if (value max) {
errorDiv.textContent = "Value out of range (min: " + min + ", max: " + max + ")";
input.style.borderColor = 'red';
return false;
}
input.style.borderColor = '#ccc'; // Reset to default
return true;
}
function getSelectedMetalDensity() {
var metalType = document.getElementById("metalType").value;
if (metalType && metalDensities[metalType]) {
return metalDensities[metalType];
}
return 0; // Return 0 if no metal selected or density not found
}
function updateSelectedMetalDensity() {
selectedMetalDensity = getSelectedMetalDensity();
document.getElementById("densityResult").textContent = selectedMetalDensity > 0 ? selectedMetalDensity + " g/cm³" : "–";
}
function calculateVolume() {
var shape = document.getElementById("shape").value;
var length, width, height, diameter, radius;
var volume = 0;
var conversionFactor = 1; // To convert input units (default mm) to cm
// Assume inputs are in mm by default based on updateShapeInputs()
if (shape === "rectangular_prism") {
length = parseFloat(document.getElementById("length").value);
width = parseFloat(document.getElementById("width").value);
height = parseFloat(document.getElementById("height").value);
if (!isNaN(length) && !isNaN(width) && !isNaN(height) && length > 0 && width > 0 && height > 0) {
volume = length * width * height; // Volume in mm³
conversionFactor = 0.001 * 0.001 * 0.001; // mm³ to cm³
}
} else if (shape === "cube") {
length = parseFloat(document.getElementById("height").value); // Using height input for cube side
if (!isNaN(length) && length > 0) {
volume = length * length * length; // Volume in mm³
conversionFactor = 0.001 * 0.001 * 0.001; // mm³ to cm³
}
} else if (shape === "cylinder") {
diameter = parseFloat(document.getElementById("diameter").value);
length = parseFloat(document.getElementById("length").value);
if (!isNaN(diameter) && !isNaN(length) && diameter > 0 && length > 0) {
radius = diameter / 2;
volume = Math.PI * radius * radius * length; // Volume in mm³
conversionFactor = 0.001 * 0.001 * 0.001; // mm³ to cm³
}
} else if (shape === "sphere") {
diameter = parseFloat(document.getElementById("diameter").value);
if (!isNaN(diameter) && diameter > 0) {
radius = diameter / 2;
volume = (4 / 3) * Math.PI * radius * radius * radius; // Volume in mm³
conversionFactor = 0.001 * 0.001 * 0.001; // mm³ to cm³
}
}
if (volume > 0 && selectedMetalDensity > 0) {
var volumeInCm3 = volume * conversionFactor;
document.getElementById("volumeResult").textContent = volume.toFixed(2) + " " + inputUnits + "³ -> " + volumeInCm3.toFixed(2) + " cm³";
return volumeInCm3;
} else {
document.getElementById("volumeResult").textContent = "–";
return 0;
}
}
function calculateWeight() {
var metalType = document.getElementById("metalType").value;
var shape = document.getElementById("shape").value;
var errors = false;
if (!metalType) { document.getElementById("metalTypeError").textContent = "Please select a metal type."; errors = true; }
if (!shape) { document.getElementById("shapeError").textContent = "Please select a shape."; errors = true; }
// Validate all visible input fields
var inputs = document.querySelectorAll('#shapeInputs input[type="number"]');
inputs.forEach(function(input) {
if (!validateInput(input, 0.01, 10000)) {
errors = true;
}
});
if (errors) {
document.getElementById("main-result").textContent = "Invalid Input";
return;
}
updateSelectedMetalDensity(); // Ensure density is up-to-date
var volumeCm3 = calculateVolume();
var weight = 0;
if (volumeCm3 > 0 && selectedMetalDensity > 0) {
weight = volumeCm3 * selectedMetalDensity; // Weight in grams
// Convert grams to desired output units (kg or tonnes)
var displayWeight = weight;
var displayUnit = 'g';
if (outputUnits === 'kg') {
displayWeight = weight / 1000;
displayUnit = 'kg';
} else if (outputUnits === 'tonne') {
displayWeight = weight / 1000000;
displayUnit = 'tonne';
} else if (outputUnits === 'lb') {
displayWeight = weight * 0.00220462; // Convert grams to pounds
displayUnit = 'lb';
}
document.getElementById("main-result").textContent = displayWeight.toFixed(3) + " " + displayUnit;
document.getElementById("unitsResult").textContent = "Weight: " + displayUnit + ", Volume: cm³";
} else {
document.getElementById("main-result").textContent = "–";
document.getElementById("unitsResult").textContent = "–";
}
updateChartData(); // Update chart after calculation
}
function resetCalculator() {
document.getElementById("metalType").value = "";
document.getElementById("shape").value = "";
document.getElementById("shapeInputs").innerHTML = "";
document.getElementById("metalTypeError").textContent = ";
document.getElementById("shapeError").textContent = ";
document.getElementById("main-result").textContent = "–";
document.getElementById("volumeResult").textContent = "–";
document.getElementById("densityResult").textContent = "–";
document.getElementById("unitsResult").textContent = "–";
// Reset chart
if (window.weightChartInstance) {
window.weightChartInstance.destroy();
window.weightChartInstance = null;
}
var ctx = document.getElementById("weightChart").getContext("2d");
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
document.getElementById("weightChart").style.display = 'none'; // Hide canvas initially
}
function copyResults() {
var mainResult = document.getElementById("main-result").textContent;
var volumeResult = document.getElementById("volumeResult").textContent;
var densityResult = document.getElementById("densityResult").textContent;
var unitsResult = document.getElementById("unitsResult").textContent;
if (mainResult === "–") return;
var resultString = "Metal Weight Calculation Results:\n\n";
resultString += "Weight: " + mainResult + "\n";
resultString += "Volume: " + volumeResult + "\n";
resultString += "Density Used: " + densityResult + "\n";
resultString += "Units: " + unitsResult + "\n\n";
resultString += "Assumptions:\n";
resultString += "- Standard density values used for selected metal.\n";
resultString += "- Input dimensions are precise.\n";
resultString += "- Calculations based on standard geometric formulas.\n";
try {
navigator.clipboard.writeText(resultString).then(function() {
// Optionally provide feedback to the user
var button = event.target;
button.textContent = 'Copied!';
setTimeout(function() { button.textContent = 'Copy Results'; }, 2000);
}).catch(function(err) {
console.error('Failed to copy: ', err);
alert('Failed to copy results. Please copy manually.');
});
} catch (err) {
console.error('Clipboard API not available: ', err);
alert('Clipboard API not available. Please copy results manually.');
}
}
// Charting Logic
var weightChartInstance = null;
function updateChartData() {
var metalType = document.getElementById("metalType").value;
var shape = document.getElementById("shape").value;
// Basic validation before updating chart
if (!metalType || !shape || !document.getElementById("densityResult").textContent.includes('g/cm³')) {
if (weightChartInstance) weightChartInstance.destroy();
weightChartInstance = null;
document.getElementById("weightChart").style.display = 'none';
return;
}
// Get dimensions and calculate volume again (ensure consistency)
var volumeCm3 = calculateVolume();
if (volumeCm3 <= 0) {
if (weightChartInstance) weightChartInstance.destroy();
weightChartInstance = null;
document.getElementById("weightChart").style.display = 'none';
return;
}
var density = getSelectedMetalDensity();
if (density <= 0) {
if (weightChartInstance) weightChartInstance.destroy();
weightChartInstance = null;
document.getElementById("weightChart").style.display = 'none';
return;
}
// Sample data points for chart: Compare weight at different volume scales
// e.g., 0.1x, 0.5x, 1x (current), 2x, 5x volume
var chartData = {
labels: ['0.1x Volume', '0.5x Volume', '1x Volume', '2x Volume', '5x Volume'],
datasets: [
{
label: 'Calculated Weight (kg)',
data: [],
borderColor: 'rgb(75, 192, 192)',
backgroundColor: 'rgba(75, 192, 192, 0.2)',
fill: false,
tension: 0.1
},
{
label: 'Weight if Density Doubled (kg)', // Hypothetical comparison
data: [],
borderColor: 'rgb(255, 99, 132)',
backgroundColor: 'rgba(255, 99, 132, 0.2)',
fill: false,
tension: 0.1
}
]
};
var currentWeightKg = (volumeCm3 * density) / 1000; // Current weight in kg
chartData.datasets[0].data.push((0.1 * currentWeightKg));
chartData.datasets[0].data.push((0.5 * currentWeightKg));
chartData.datasets[0].data.push(currentWeightKg);
chartData.datasets[0].data.push((2.0 * currentWeightKg));
chartData.datasets[0].data.push((5.0 * currentWeightKg));
// Data for the second series (hypothetical doubled density)
var doubledDensity = density * 2;
chartData.datasets[1].data.push((0.1 * volumeCm3 * doubledDensity) / 1000);
chartData.datasets[1].data.push((0.5 * volumeCm3 * doubledDensity) / 1000);
chartData.datasets[1].data.push((currentWeightKg * 2)); // Double the current weight
chartData.datasets[1].data.push((2.0 * volumeCm3 * doubledDensity) / 1000);
chartData.datasets[1].data.push((5.0 * volumeCm3 * doubledDensity) / 1000);
var ctx = document.getElementById("weightChart").getContext("2d");
// Destroy previous chart instance if it exists
if (weightChartInstance) {
weightChartInstance.destroy();
}
document.getElementById("weightChart").style.display = 'block'; // Make canvas visible
weightChartInstance = new Chart(ctx, {
type: 'line',
data: chartData,
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Weight (kg)'
}
},
x: {
title: {
display: true,
text: 'Volume Scale Factor'
}
}
},
plugins: {
title: {
display: true,
text: 'Weight vs. Volume Scale for ' + document.getElementById("metalType").options[document.getElementById("metalType").selectedIndex].text
},
legend: {
position: 'top',
}
}
}
});
}
// Initialize the calculator on load
document.addEventListener("DOMContentLoaded", function() {
// Set default values or trigger initial update
updateShapeInputs(); // This will also call calculateWeight and updateChartData
// Set default units – example: kg for weight, mm for dimensions
outputUnits = 'kg';
inputUnits = 'mm';
volumeUnit = 'cm³';
calculateWeight(); // Trigger calculation once on load
});
// Add event listeners for metal type and shape changes to trigger updates
document.getElementById("metalType").addEventListener("change", function() {
updateSelectedMetalDensity();
calculateWeight();
});
document.getElementById("shape").addEventListener("change", function() {
updateShapeInputs();
});