Cardboard Box Weight Calculator

Cardboard Box Weight Calculator: Estimate Shipping & Storage Needs body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: #f8f9fa; color: #333; line-height: 1.6; margin: 0; padding: 0; } .container { max-width: 1000px; margin: 20px auto; padding: 20px; background-color: #fff; box-shadow: 0 2px 10px rgba(0,0,0,.05); border-radius: 8px; } h1, h2, h3 { color: #004a99; } .calculator-wrapper { background-color: #ffffff; padding: 30px; border-radius: 8px; box-shadow: 0 4px 15px rgba(0,0,0,.1); margin-bottom: 40px; } .calculator-wrapper h2 { text-align: center; margin-bottom: 25px; color: #004a99; } .input-group { margin-bottom: 18px; } .input-group label { display: block; margin-bottom: 8px; font-weight: 600; color: #555; } .input-group input[type="number"], .input-group select { width: calc(100% – 22px); /* Adjust for padding and border */ padding: 10px 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 1rem; box-sizing: border-box; /* Include padding and border in the element's total width and height */ } .input-group .helper-text { font-size: 0.85em; color: #777; margin-top: 5px; } .input-group .error-message { color: #dc3545; font-size: 0.8em; margin-top: 5px; display: none; /* Hidden by default */ } .input-group input[type="number"]:focus, .input-group select:focus { outline: none; border-color: #007bff; box-shadow: 0 0 0 0.2rem rgba(0,123,255,.25); } .button-group { display: flex; justify-content: space-between; margin-top: 25px; gap: 10px; /* Space between buttons */ } .button-group button { padding: 10px 20px; border: none; border-radius: 4px; font-size: 1rem; cursor: pointer; transition: background-color 0.3s ease; flex: 1; /* Distribute space equally */ } .btn-calculate { background-color: #004a99; color: white; } .btn-calculate:hover { background-color: #003366; } .btn-reset { background-color: #6c757d; color: white; } .btn-reset:hover { background-color: #5a6268; } .btn-copy { background-color: #28a745; color: white; } .btn-copy:hover { background-color: #218838; } .results-wrapper { margin-top: 30px; padding: 20px; background-color: #e9ecef; border-radius: 8px; text-align: center; border: 1px dashed #adb5bd; } .results-wrapper h3 { margin-top: 0; color: #004a99; } #primary-result { font-size: 2.5rem; font-weight: bold; color: #004a99; margin: 10px 0; display: inline-block; /* To allow background color to fit content */ padding: 10px 20px; background-color: #ffc107; /* A color to highlight */ border-radius: 5px; } .intermediate-results div { margin-top: 15px; font-size: 1.1rem; } .intermediate-results span { font-weight: bold; color: #004a99; } .formula-explanation { font-size: 0.95em; color: #555; margin-top: 20px; font-style: italic; } table { width: 100%; border-collapse: collapse; margin-top: 30px; box-shadow: 0 2px 5px rgba(0,0,0,.05); } thead { background-color: #004a99; color: white; } th, td { padding: 12px 15px; text-align: left; border: 1px solid #ddd; } tbody tr:nth-child(even) { background-color: #f2f2f2; } caption { caption-side: bottom; font-size: 0.9em; color: #777; margin-top: 10px; font-style: italic; } canvas { display: block; margin: 30px auto; background-color: #fff; border-radius: 5px; box-shadow: 0 2px 5px rgba(0,0,0,.05); } .section { margin-top: 40px; padding-top: 20px; border-top: 1px solid #eee; } .section h2 { margin-bottom: 20px; } .section p, .section li { margin-bottom: 15px; } .section a { color: #004a99; text-decoration: none; } .section a:hover { text-decoration: underline; } .faq-item { margin-bottom: 20px; padding: 15px; background-color: #fdfdfd; border: 1px solid #eee; border-radius: 5px; } .faq-item h3 { margin-top: 0; margin-bottom: 10px; font-size: 1.2rem; cursor: pointer; /* Indicate it's clickable */ color: #004a99; } .faq-item p { margin-bottom: 0; display: none; /* Hidden by default */ } .faq-item.open p { display: block; } .internal-links ul { list-style: none; padding: 0; } .internal-links li { margin-bottom: 10px; } .internal-links a { font-weight: 600; } /* Responsive adjustments */ @media (max-width: 768px) { .container { margin: 10px; padding: 15px; } .button-group { flex-direction: column; /* Stack buttons vertically on smaller screens */ } .button-group button { width: 100%; } #primary-result { font-size: 2rem; } }

Cardboard Box Weight Calculator: Estimate Shipping & Storage Needs

Cardboard Box Weight Calculator

Enter the longest dimension of the box in centimeters.
Enter the second longest dimension of the box in centimeters.
Enter the shortest dimension of the box in centimeters.
Weight of the cardboard material per square meter (e.g., 150 for standard single wall).
Single Ply Double Ply Triple Ply
Commonly single (corrugated) or double (heavy-duty).

Estimated Box Weight

Surface Area:
Estimated Material Weight: kg
Box Volume:
The estimated box weight is calculated by finding the total surface area of the box, accounting for the number of plies, and then multiplying by the material's weight per square meter. Weight (kg) = (Surface Area (m²) * Ply Factor * Material Weight (g/m²)) / 1000

Understanding the Cardboard Box Weight Calculator

The {primary_keyword} is a valuable tool for anyone involved in logistics, shipping, e-commerce, warehousing, or event planning. It helps estimate the weight of a cardboard box based on its dimensions (length, width, height), the type of cardboard material used (indicated by its weight per square meter), and the number of plies (layers) of cardboard. Accurate weight estimation is crucial for various reasons, including determining shipping costs, ensuring safe handling, optimizing storage space, and complying with regulations. This calculator simplifies that process by providing a quick and reliable estimate, allowing for better planning and cost management.

Who Should Use This Calculator?

  • E-commerce Businesses: To accurately calculate shipping fees, choose appropriate packaging, and manage inventory.
  • Logistics and Shipping Companies: For planning vehicle loads, estimating fuel consumption, and optimizing delivery routes.
  • Warehouse Managers: To assess storage capacity, plan shelving requirements, and manage forklift operations.
  • Packaging Designers and Manufacturers: To test material efficiency and ensure products meet weight specifications.
  • Event Planners and Exhibition Organizers: To estimate the volume and weight of materials needed for transport and setup.
  • Individuals Moving Homes: To get a rough idea of how much their packed boxes will weigh for moving quotes.

Common Misconceptions

A common misconception is that all cardboard boxes of the same external dimensions weigh the same. This calculator highlights that material density (g/m²) and construction (plies) significantly impact the final weight. Another is that weight is solely determined by volume; while related, the material's properties are a major factor. Some might also overlook the impact of flaps, internal supports, or double-boxing, which this simplified model doesn't precisely account for but provides a strong baseline.

Cardboard Box Weight Calculator: Formula and Mathematical Explanation

The core of the {primary_keyword} lies in calculating the total surface area of the box and then applying the material's weight characteristics. Here's a breakdown of the formula and its components:

The Formula

Estimated Box Weight (kg) = (Total Surface Area (m²) × Ply Factor × Material Weight (g/m²)) / 1000

Let's break down each variable:

Variable Explanations

Surface Area (m²): This is the total area of all six faces of the box. It's calculated as 2 * (Length × Width + Length × Height + Width × Height). This value is then converted from cm² to m².
Ply Factor: A multiplier representing the number of layers of cardboard. Single-ply boxes use a factor of 1, double-ply use 2, and triple-ply use 3.
Material Weight (g/m²): This indicates the density or thickness of the cardboard material itself. Higher values mean heavier, often stronger, cardboard.
1000: This constant is used to convert the total weight from grams (calculated by multiplying area in m² by g/m²) to kilograms.

Variables Table

Variable Meaning Unit Typical Range
Box Length, Width, Height External dimensions of the box cm 10 – 200+
Material Weight Weight of the cardboard material per square meter g/m² 100 – 400+ (Standard single wall: 125-200 g/m²; Double wall: 200-400 g/m²)
Number of Plies Number of cardboard layers Unitless 1, 2, or 3
Ply Factor Multiplier for plies Unitless 1, 2, or 3 (corresponds to ply number)
Surface Area Total area of all box faces Dependent on dimensions
Estimated Box Weight Final calculated weight of the empty box kg Highly variable, depends on all factors
Key variables used in the cardboard box weight calculation.

Practical Examples (Real-World Use Cases)

Example 1: Standard Shipping Box

A small online retailer needs to ship a product. They use a standard single-wall cardboard box with the following dimensions:

  • Length: 30 cm
  • Width: 20 cm
  • Height: 15 cm
  • Material Weight: 150 g/m² (typical for single wall)
  • Number of Plies: 1 (Single Ply)

Calculation Steps:

  1. Convert dimensions to meters: L=0.3m, W=0.2m, H=0.15m
  2. Calculate Surface Area: 2 * (0.3*0.2 + 0.3*0.15 + 0.2*0.15) = 2 * (0.06 + 0.045 + 0.03) = 2 * 0.135 = 0.27 m²
  3. Ply Factor = 1
  4. Estimated Weight = (0.27 m² * 1 * 150 g/m²) / 1000 = 40.5 g / 1000 = 0.0405 kg

Result: The estimated weight of this standard box is approximately 0.04 kg (40.5 grams). This minimal weight is important for accurately calculating shipping costs, especially for lightweight items where the box weight itself might be a small but necessary component of the total parcel weight. This understanding helps avoid underestimating shipping fees.

Example 2: Heavy-Duty Moving Box

A family is moving and needs sturdy boxes for books and heavier items. They opt for a larger, double-wall cardboard box:

  • Length: 50 cm
  • Width: 40 cm
  • Height: 40 cm
  • Material Weight: 300 g/m² (typical for double wall)
  • Number of Plies: 2 (Double Ply)

Calculation Steps:

  1. Convert dimensions to meters: L=0.5m, W=0.4m, H=0.4m
  2. Calculate Surface Area: 2 * (0.5*0.4 + 0.5*0.4 + 0.4*0.4) = 2 * (0.2 + 0.2 + 0.16) = 2 * 0.56 = 1.12 m²
  3. Ply Factor = 2
  4. Estimated Weight = (1.12 m² * 2 * 300 g/m²) / 1000 = 672 g / 1000 = 0.672 kg

Result: This larger, double-wall moving box weighs approximately 0.67 kg (672 grams). This is significantly heavier than the first example, emphasizing the importance of material choice and size. Knowing this helps movers estimate the total weight of packed boxes, plan for safe lifting, and ensure they don't exceed weight limits for moving trucks or specific shipping services. This is crucial for budgeting and logistics planning during a move.

How to Use This Cardboard Box Weight Calculator

Using the {primary_keyword} is straightforward. Follow these simple steps to get your estimated box weight:

  1. Measure Your Box: Accurately measure the external length, width, and height of your cardboard box in centimeters (cm).
  2. Identify Material Weight: Determine the weight of the cardboard material per square meter (g/m²). This information is often available from the box manufacturer or supplier. If unsure, common values are around 150 g/m² for standard single-wall boxes and 250-400 g/m² for double-wall or heavy-duty boxes.
  3. Select Number of Plies: Choose the correct number of plies (layers) for your box: Single Ply (1), Double Ply (2), or Triple Ply (3). This dictates the 'Ply Factor'.
  4. Enter Values into Calculator: Input the measured dimensions and identified material specifications into the corresponding fields: 'Box Length (cm)', 'Box Width (cm)', 'Box Height (cm)', and 'Material Weight (g/m²)'. Select the 'Number of Plies' from the dropdown.
  5. Calculate: Click the "Calculate Weight" button.

Reading the Results:

  • Estimated Box Weight (kg): This is the primary result, displayed prominently. It represents the approximate weight of the empty cardboard box in kilograms.
  • Surface Area (m²): This intermediate value shows the total surface area of the box in square meters, a key component of the calculation.
  • Estimated Material Weight (kg): This shows the calculated weight based on the surface area and material g/m², before accounting for plies.
  • Box Volume (m³): Displays the internal volume capacity of the box in cubic meters. While not directly used in weight calculation, it's useful for understanding packing density.

Decision-Making Guidance:

  • Shipping Costs: Use the estimated weight to get more accurate shipping quotes from carriers.
  • Handling and Safety: Knowing the weight helps determine if a box can be safely lifted manually or requires mechanical assistance.
  • Storage Optimization: Understand the weight distribution for efficient stacking and warehouse management.
  • Material Choice: Compare the estimated weights of different box types to select the most appropriate and cost-effective option for your needs.

Use the "Copy Results" button to easily share or record the calculated details, including key assumptions. The "Reset" button clears all fields and reverts to default values for a fresh calculation.

Key Factors That Affect Cardboard Box Weight Results

While the calculator provides a solid estimate for the cardboard box weight calculator, several real-world factors can influence the actual weight:

  1. Material Density and Quality (g/m²): This is the most significant factor after dimensions. Higher g/m² values indicate denser, often thicker, cardboard, resulting in a heavier box. The quality of the pulp and manufacturing process also plays a role. Using a higher g/m² value than specified will overestimate weight, while using a lower one will underestimate it.
  2. Number of Plies: As incorporated in the 'Ply Factor', more layers of cardboard (double-wall, triple-wall) drastically increase the box's weight compared to a single-wall equivalent of the same outer dimensions. This is essential for structural integrity but adds weight.
  3. Internal Structures and Reinforcements: The calculator estimates weight based on external dimensions. However, internal dividers, corner posts, or extra padding used for product protection add material and thus weight. These are not factored into the basic surface area calculation.
  4. Moisture Content: Cardboard is hygroscopic, meaning it absorbs moisture from the air. Boxes stored in humid environments will weigh more than identical boxes stored in dry conditions. This variance is usually minor but can be noticeable in large shipments.
  5. Adhesives and Tape: The glue used to assemble the box structure and any tape applied for sealing contribute a small amount to the overall weight. This is typically negligible for standard calculations but could be relevant for ultra-precise weight management.
  6. Manufacturing Tolerances: Cardboard box manufacturing isn't perfectly precise. Slight variations in dimensions (length, width, height) and material thickness can lead to minor deviations from the calculated weight.
  7. Recycled Content: While not directly measured by g/m², the type and amount of recycled content can subtly affect the density and structural integrity, potentially influencing weight and performance.

Frequently Asked Questions (FAQ)

What is the typical weight of a standard cardboard box?

A standard single-wall box (e.g., 30x20x15 cm) with material weight of 150 g/m² might weigh around 40-60 grams. Larger, heavier-duty boxes (e.g., 50x40x40 cm, double-wall) can weigh from 0.5 kg to over 1 kg. The calculator helps pinpoint this based on specific dimensions and material.

How accurate is this cardboard box weight calculator?

The calculator provides a highly accurate estimate based on the provided dimensions and material specifications. It accounts for surface area, material density, and plies. However, actual weight can vary slightly due to manufacturing tolerances, moisture content, and added adhesives/tape. It's an excellent tool for planning and estimation.

What does "Material Weight (g/m²)" mean?

This refers to the weight of one square meter of the flat cardboard material before it's formed into a box. It's a key indicator of the cardboard's thickness and strength. Higher g/m² values generally mean a heavier and more robust cardboard, suitable for heavier items or more demanding shipping conditions.

Can I use this calculator for different box shapes?

This calculator is designed for standard rectangular (prismatic) cardboard boxes. It relies on calculating the surface area of a cuboid. For irregularly shaped packaging, a different calculation method would be required.

How do plies affect the weight?

Plies refer to the layers of cardboard. A single-ply box has one corrugated layer between two liners. A double-ply box has two such layers, and a triple-ply has three. Each additional ply adds significant material, increasing the box's weight and strength considerably. The calculator uses the number of plies to adjust the weight calculation accordingly.

Why is estimating box weight important for shipping?

Accurate box weight is crucial for calculating shipping costs, as carriers often charge based on weight and dimensions (dimensional weight). Underestimating weight can lead to unexpected surcharges or refused shipments. Overestimating can lead to paying more than necessary. It also impacts load planning for trucks and aircraft.

Does the calculator account for the weight of the contents?

No, this calculator specifically estimates the weight of the empty cardboard box itself. The weight of the contents must be added separately to determine the total shipping weight.

What if I don't know the exact material weight (g/m²)?

If you don't have the exact g/m² specification, you can use typical values based on the box type. For standard single-wall boxes, 125-200 g/m² is common. For double-wall or heavy-duty boxes, 200-400 g/m² is a reasonable range. Using an average or a slightly conservative estimate can still provide a useful approximation for your {primary_keyword} needs.

// JavaScript for the Cardboard Box Weight Calculator function getElement(id) { return document.getElementById(id); } function validateInput(inputId, errorId, minValue, maxValue) { var input = getElement(inputId); var errorElement = getElement(errorId); var value = parseFloat(input.value); errorElement.style.display = 'none'; // Hide error by default if (isNaN(value)) { errorElement.textContent = "Please enter a valid number."; errorElement.style.display = 'block'; return false; } if (value maxValue) { // errorElement.textContent = "Value cannot exceed " + maxValue + "."; // errorElement.style.display = 'block'; // return false; // } return true; } function updatePlyHelperText() { var plySelect = getElement('ply'); var helperTextElement = getElement('plyHelperText'); var selectedValue = plySelect.value; if (selectedValue === '1') { helperTextElement.textContent = "Commonly single (corrugated) for standard boxes."; } else if (selectedValue === '2') { helperTextElement.textContent = "Double ply provides extra strength for heavier items."; } else { helperTextElement.textContent = "Triple ply offers maximum strength for very heavy or fragile goods."; } } function calculateWeight() { var lengthCm = getElement('boxLength').value; var widthCm = getElement('boxWidth').value; var heightCm = getElement('boxHeight').value; var materialWeightGperM2 = getElement('materialWeightPerSqM').value; var ply = parseInt(getElement('ply').value); // Validation var isValid = true; isValid &= validateInput('boxLength', 'boxLengthError'); isValid &= validateInput('boxWidth', 'boxWidthError'); isValid &= validateInput('boxHeight', 'boxHeightError'); isValid &= validateInput('materialWeightPerSqM', 'materialWeightPerSqMError'); if (!isValid) { getElement('results-wrapper').style.display = 'none'; return; } // Convert cm to meters var lengthM = parseFloat(lengthCm) / 100; var widthM = parseFloat(widthCm) / 100; var heightM = parseFloat(heightCm) / 100; var materialWeight = parseFloat(materialWeightGperM2); // Calculate Surface Area in m² var surfaceAreaM2 = 2 * (lengthM * widthM + lengthM * heightM + widthM * heightM); // Calculate total weight in grams var totalWeightGrams = surfaceAreaM2 * ply * materialWeight; // Convert to kilograms var estimatedWeightKg = totalWeightGrams / 1000; // Calculate intermediate values var estimatedMaterialWeightKg = (surfaceAreaM2 * materialWeight) / 1000; // Weight if it were single ply var boxVolumeM3 = lengthM * widthM * heightM; // Display results getElement('primary-result').textContent = estimatedWeightKg.toFixed(3) + ' kg'; getElement('surfaceArea').getElementsByTagName('span')[0].textContent = surfaceAreaM2.toFixed(3); getElement('materialWeight').getElementsByTagName('span')[0].textContent = estimatedMaterialWeightKg.toFixed(3); getElement('volume').getElementsByTagName('span')[0].textContent = boxVolumeM3.toFixed(3); getElement('results-wrapper').style.display = 'block'; // Update chart updateChart(surfaceAreaM2, estimatedWeightKg, materialWeight, ply); return { estimatedWeightKg: estimatedWeightKg.toFixed(3), surfaceAreaM2: surfaceAreaM2.toFixed(3), estimatedMaterialWeightKg: estimatedMaterialWeightKg.toFixed(3), boxVolumeM3: boxVolumeM3.toFixed(3), materialWeightGperM2: materialWeight, ply: ply }; } function resetCalculator() { getElement('boxLength').value = '30'; getElement('boxWidth').value = '20'; getElement('boxHeight').value = '15'; getElement('materialWeightPerSqM').value = '150'; getElement('ply').value = '1'; updatePlyHelperText(); // Update helper text after reset // Clear errors getElement('boxLengthError').style.display = 'none'; getElement('boxWidthError').style.display = 'none'; getElement('boxHeightError').style.display = 'none'; getElement('materialWeightPerSqMError').style.display = 'none'; getElement('results-wrapper').style.display = 'none'; getElement('weightChart').style.display = 'none'; // Hide chart on reset } function copyResults() { var resultsData = calculateWeight(); // Recalculate to ensure latest values if (!resultsData) return; // Don't copy if calculation failed var copyText = "Cardboard Box Weight Calculation:\n\n"; copyText += "Estimated Box Weight: " + resultsData.estimatedWeightKg + " kg\n"; copyText += "Surface Area: " + resultsData.surfaceAreaM2 + " m²\n"; copyText += "Estimated Material Weight (single ply equiv.): " + resultsData.estimatedMaterialWeightKg + " kg\n"; copyText += "Box Volume: " + resultsData.boxVolumeM3 + " m³\n\n"; copyText += "Assumptions:\n"; copyText += "- Material Weight: " + resultsData.materialWeightGperM2 + " g/m²\n"; copyText += "- Number of Plies: " + resultsData.ply + "\n"; copyText += "- Dimensions (cm): L=" + getElement('boxLength').value + ", W=" + getElement('boxWidth').value + ", H=" + getElement('boxHeight').value + "\n"; // Use a temporary textarea to copy text var textArea = document.createElement("textarea"); textArea.value = copyText; textArea.style.position = "fixed"; // Avoid scrolling to bottom of page 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!'; alert(msg); // Basic feedback } catch (err) { alert('Oops, unable to copy'); } document.body.removeChild(textArea); } // Charting Functionality function updateChart(surfaceArea, estimatedWeight, materialWeight, ply) { var canvas = getElement('weightChart'); if (!canvas) return; // Canvas not found canvas.style.display = 'block'; // Make canvas visible var ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, canvas.width, canvas.height); // Clear previous chart // Simulate data points for chart – e.g., how weight changes with material density or plies var dataSeries1Label = "Weight vs. Material Weight (g/m²) for Ply " + ply; var dataSeries2Label = "Weight vs. Plies for Material " + materialWeight + " g/m²"; var materialWeights = [100, 150, 200, 250, 300, 350, 400]; // Example range var weightsVsMaterial = []; for (var i = 0; i < materialWeights.length; i++) { weightsVsMaterial.push((surfaceArea * ply * materialWeights[i]) / 1000); } var plies = [1, 2, 3]; var weightsVsPlies = []; for (var i = 0; i = plies.length) { chartData.labels = materialWeights.map(function(w) { return w + " g/m²"; }); } else { chartData.labels = plies.map(function(p) { return p + " Ply"; }); } // Ensure labels align with the correct data if lengths differ if (weightsVsPlies.length < chartData.labels.length) { while(weightsVsPlies.length < chartData.labels.length) { weightsVsPlies.push(NaN); // Pad with NaN if needed } } if (weightsVsMaterial.length < chartData.labels.length) { while(weightsVsMaterial.length < chartData.labels.length) { weightsVsMaterial.push(NaN); // Pad with NaN if needed } } // Basic Chart Drawing (No external library) var padding = 40; var chartAreaWidth = canvas.width – 2 * padding; var chartAreaHeight = canvas.height – 2 * padding; // Find max value for scaling var maxWeight = 0; for (var i = 0; i < chartData.datasets.length; i++) { for (var j = 0; j maxWeight) { maxWeight = chartData.datasets[i].data[j]; } } } if (maxWeight === 0) maxWeight = 1; // Avoid division by zero // Draw Axes ctx.beginPath(); ctx.strokeStyle = '#aaa'; ctx.moveTo(padding, padding); ctx.lineTo(padding, canvas.height – padding); // Y-axis ctx.lineTo(canvas.width – padding, canvas.height – padding); // X-axis ctx.stroke(); // Draw Y-axis labels and ticks ctx.fillStyle = '#555'; ctx.textAlign = 'right'; ctx.textBaseline = 'middle'; var numYTicks = 5; for (var i = 0; i <= numYTicks; i++) { var yPos = canvas.height – padding – (i / numYTicks) * chartAreaHeight; var yLabel = (maxWeight * i / numYTicks).toFixed(2); ctx.fillText(yLabel, padding – 5, yPos); ctx.beginPath(); ctx.moveTo(padding – 3, yPos); ctx.lineTo(padding, yPos); ctx.stroke(); } // Draw X-axis labels ctx.textAlign = 'center'; ctx.textBaseline = 'top'; var numXTicks = chartData.labels.length; for (var i = 0; i < numXTicks; i++) { var xPos = padding + (i / (numXTicks – 1)) * chartAreaWidth; ctx.fillText(chartData.labels[i], xPos, canvas.height – padding + 5); } // Draw Datasets ctx.lineWidth = 2; for (var i = 0; i < chartData.datasets.length; i++) { ctx.beginPath(); ctx.strokeStyle = chartData.datasets[i].borderColor; var firstPoint = true; for (var j = 0; j < chartData.datasets[i].data.length; j++) { var xPos = padding + (j / (numXTicks – 1)) * chartAreaWidth; var yPos = canvas.height – padding – (chartData.datasets[i].data[j] / maxWeight) * chartAreaHeight; if (!isNaN(chartData.datasets[i].data[j])) { if (firstPoint) { ctx.moveTo(xPos, yPos); firstPoint = false; } else { ctx.lineTo(xPos, yPos); } } else { firstPoint = true; // Reset if NaN encountered (for discontinuous lines) } } ctx.stroke(); } // Draw Legend ctx.textAlign = 'left'; ctx.textBaseline = 'top'; ctx.font = '12px Segoe UI'; var legendY = padding / 2; for (var i = 0; i < chartData.datasets.length; i++) { ctx.fillStyle = chartData.datasets[i].borderColor; ctx.fillRect(padding + i * (chartAreaWidth / chartData.datasets.length), legendY, 10, 10); ctx.fillStyle = '#333'; ctx.fillText(chartData.datasets[i].label, padding + i * (chartAreaWidth / chartData.datasets.length) + 15, legendY – 5); } } // Initial setup document.addEventListener('DOMContentLoaded', function() { updatePlyHelperText(); // Set initial helper text // Optionally auto-calculate on load if default values are present // calculateWeight(); });

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