Head Weight Calculator

Head Weight Calculator: Estimate Your Head's Mass 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: 960px; margin: 20px auto; padding: 20px; background-color: #fff; border-radius: 8px; box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1); } header { background-color: #004a99; color: #fff; padding: 20px 0; text-align: center; border-radius: 8px 8px 0 0; margin-bottom: 20px; } header h1 { margin: 0; font-size: 2.5em; } .loan-calc-container { margin-bottom: 30px; padding: 20px; border: 1px solid #ddd; border-radius: 5px; background-color: #fdfdfd; } .input-group { margin-bottom: 15px; display: flex; flex-direction: column; align-items: flex-start; } .input-group label { display: block; margin-bottom: 5px; font-weight: bold; color: #004a99; } .input-group input[type="number"], .input-group select { width: 100%; padding: 10px; border: 1px solid #ccc; border-radius: 4px; box-sizing: border-box; font-size: 1em; } .input-group .helper-text { font-size: 0.85em; color: #666; margin-top: 5px; } .error-message { color: #dc3545; font-size: 0.8em; margin-top: 5px; display: none; /* Hidden by default */ } .error-message.visible { display: block; } .button-group { display: flex; justify-content: space-between; margin-top: 20px; flex-wrap: wrap; gap: 10px; } .button-group button { padding: 12px 20px; border: none; border-radius: 4px; cursor: pointer; font-size: 1em; transition: background-color 0.3s ease; flex-grow: 1; min-width: 150px; } .calculate-btn { background-color: #004a99; color: white; } .calculate-btn:hover { background-color: #003366; } .reset-btn { background-color: #ffc107; color: #212529; } .reset-btn:hover { background-color: #e0a800; } .copy-btn { background-color: #28a745; color: white; } .copy-btn:hover { background-color: #218838; } .results-container { margin-top: 30px; padding: 20px; border: 1px solid #ddd; border-radius: 5px; background-color: #eef5ff; } .results-container h3 { color: #004a99; margin-top: 0; } .primary-result { font-size: 2.5em; font-weight: bold; color: #004a99; text-align: center; margin-bottom: 20px; padding: 15px; background-color: #cce5ff; border-radius: 5px; } .intermediate-results div, .assumptions div { margin-bottom: 10px; font-size: 1.1em; } .intermediate-results span, .assumptions span { font-weight: bold; } .formula-explanation { font-size: 0.9em; color: #555; margin-top: 15px; padding-top: 15px; border-top: 1px dashed #ccc; } table { width: 100%; border-collapse: collapse; margin-top: 20px; box-shadow: 0 1px 3px rgba(0,0,0,0.08); } th, td { padding: 12px; text-align: left; border-bottom: 1px solid #ddd; } thead { background-color: #004a99; color: #fff; } th { font-weight: bold; } caption { caption-side: top; font-weight: bold; font-size: 1.2em; margin-bottom: 10px; text-align: left; color: #004a99; } canvas { margin-top: 20px; border: 1px solid #ddd; border-radius: 5px; background-color: #fefefe; } .article-section { margin-top: 40px; padding-top: 30px; border-top: 1px solid #eee; } .article-section h2, .article-section h3 { color: #004a99; margin-bottom: 15px; } .article-section h2 { font-size: 2em; border-bottom: 2px solid #004a99; padding-bottom: 8px; } .article-section h3 { font-size: 1.5em; } .article-section p, .article-section li { margin-bottom: 15px; } .article-section ul { padding-left: 20px; } .article-section a { color: #004a99; text-decoration: none; } .article-section a:hover { text-decoration: underline; } .faq-item { margin-bottom: 15px; padding-bottom: 10px; border-bottom: 1px dashed #eee; } .faq-item:last-child { border-bottom: none; } .faq-item strong { color: #004a99; display: block; margin-bottom: 5px; } .internal-links-list { list-style: none; padding: 0; } .internal-links-list li { margin-bottom: 10px; } .internal-links-list a { font-weight: bold; } .internal-links-list p { font-size: 0.9em; color: #555; margin-top: 5px; } /* Responsive adjustments */ @media (max-width: 768px) { .container { margin: 10px; padding: 15px; } header h1 { font-size: 2em; } .button-group button { min-width: unset; width: 100%; } .primary-result { font-size: 2em; } }

Head Weight Calculator

Estimate Head Weight

Input the relevant physical characteristics to estimate the weight of a human head.

Measure around the widest part of the head, typically above the eyebrows and ears (in centimeters).
Measure from the crown of the head to the base of the chin (in centimeters).
Measure across the widest part of the head, from ear to ear (in centimeters).
Your total body weight (in kilograms).
Adult Child (under 12)
Select the appropriate age group for a more accurate estimate.

Results

— kg
Estimated Volume: L
Density Factor:
Head Weight as % of Body Weight: %
Formula Used: Head weight is estimated using a multivariate regression model derived from anatomical studies. It considers head dimensions (circumference, height, width) and total body weight, adjusted for age group. The model approximates head volume and then applies an average human tissue density factor.

Head Weight Distribution by Age Group

Average Head Weight Factors
Factor Description Typical Value Range
Head Volume Approximation Estimated volume based on head dimensions. 15 – 25 Liters
Tissue Density Average density of human head tissues (bone, brain, skin, etc.). 1.04 – 1.06 g/cm³ (approx. 1040 – 1060 kg/m³)
Body Weight Ratio Head weight as a proportion of total body weight. 7% – 10% (adults), higher for infants.

What is Head Weight?

The term head weight calculator refers to a tool designed to estimate the mass of a human head based on various physical measurements and demographic factors. While not a precise scientific instrument for individual measurement, it provides a valuable approximation for understanding average head mass, its relation to body weight, and how it might vary across different populations or for specific purposes like biomechanical simulations or anthropological studies. A human head is a complex structure comprising the skull, brain, facial features, and associated tissues. Its weight is influenced by bone density, brain size, muscle mass in the face and neck, and overall body composition.

Who should use it? This calculator can be useful for students, researchers, medical professionals, athletes, or anyone interested in anthropometry and human physiology. It can help in:

  • Educational purposes: Demonstrating anatomical relationships and scale.
  • Research: Providing baseline estimates for studies involving head size and mass.
  • Fitness and Ergonomics: Understanding body proportions and potential strain on the neck.
  • General curiosity: Satisfying an interest in human biological data.

Common misconceptions about head weight include the belief that it's a fixed percentage of body weight across all ages and body types, or that it's solely determined by head circumference. In reality, factors like brain size relative to skull size, facial bone structure, and even hydration levels can subtly influence actual head mass. The head weight calculator aims to bridge this gap by incorporating multiple parameters for a more nuanced estimation.

Head Weight Calculator Formula and Mathematical Explanation

The head weight calculator employs a simplified empirical model. Direct measurement of head weight is impractical outside of specific medical or forensic contexts. Therefore, estimation relies on correlating readily measurable external dimensions and body metrics with known anatomical data.

The general approach involves estimating head volume first, and then applying an average density factor. A common approximation for head volume (V) can be derived from head circumference (C), height (H), and width (W), though various formulas exist. A simplified model might look like this:

Estimated Volume (V) = k * (C * H * W)

Where 'k' is a constant factor that accounts for the irregular shape of the head and differences between genders or age groups. More sophisticated models use multivariate regression.

Once an estimated volume is obtained, the head weight (M) is calculated using an average density (ρ) for human tissues, which is slightly denser than water.

Estimated Head Weight (M) = V * ρ

The density (ρ) of human tissues (brain, bone, fat, muscle, skin) averages around 1.05 grams per cubic centimeter (g/cm³), which is equivalent to 1050 kilograms per cubic meter (kg/m³). Since our inputs are in centimeters, we often work with liters (1 L = 1000 cm³).

The calculator also normalizes this by relating it to body weight.

Head Weight as % of Body Weight = (Estimated Head Weight / Total Body Weight) * 100

Variables Explained:

Head Weight Calculator Variables
Variable Meaning Unit Typical Range
Head Circumference (C) Measurement around the widest part of the head. Centimeters (cm) 45 – 65 cm (adults)
Head Height (H) Measurement from crown to chin. Centimeters (cm) 15 – 25 cm (adults)
Head Width (W) Measurement across the widest part of the head. Centimeters (cm) 13 – 18 cm (adults)
Body Weight (BW) Total weight of the individual. Kilograms (kg) 40 – 120 kg (adults)
Age Group Categorical variable indicating the individual's age stage. N/A Adult, Child
Estimated Head Weight (M) The calculated mass of the head. Kilograms (kg) 3.5 – 5.5 kg (adults)
Estimated Volume (V) Approximate internal volume of the head. Liters (L) 15 – 25 L
Density Factor (ρ) Average density of human head tissues. g/cm³ or kg/m³ ~1.05 g/cm³

Practical Examples (Real-World Use Cases)

Let's explore how the head weight calculator can be used with practical examples. These examples illustrate the estimation process and how results can be interpreted.

Example 1: Estimating Head Weight for an Adult Male

Consider John, a healthy adult male, who wants to understand his body proportions. He measures his head:

  • Head Circumference: 58 cm
  • Head Height: 22 cm
  • Head Width: 16 cm
  • Body Weight: 80 kg
  • Age Group: Adult

Inputting these values into the head weight calculator yields:

  • Estimated Volume: Approximately 20.5 Liters
  • Estimated Head Weight: Approximately 4.8 kg
  • Head Weight as % of Body Weight: Approximately 6.0%

Interpretation: John's estimated head weight of 4.8 kg falls within the typical range for adult males. The calculator shows his head constitutes about 6.0% of his total body weight, which is slightly lower than the upper end of the average range (7-10%), suggesting a balanced body proportion. This information could be useful for him if he's tracking anthropometric data for fitness or health monitoring.

Example 2: Estimating Head Weight for a Young Child

Sarah is curious about her 5-year-old daughter, Emily's, head size relative to her body. Emily has the following measurements:

  • Head Circumference: 49 cm
  • Head Height: 18 cm
  • Head Width: 14 cm
  • Body Weight: 18 kg
  • Age Group: Child

Using the head weight calculator with these inputs results in:

  • Estimated Volume: Approximately 12.0 Liters
  • Estimated Head Weight: Approximately 2.8 kg
  • Head Weight as % of Body Weight: Approximately 15.6%

Interpretation: Emily's estimated head weight is 2.8 kg. The percentage of her body weight represented by her head (15.6%) is significantly higher than an adult's. This is entirely normal, as infants and young children have proportionally larger heads relative to their body size. This highlights the importance of the age group factor in the calculator's estimation and provides reassurance that Emily's head size is proportionate for her age. This data is crucial for pediatricians monitoring growth and development.

How to Use This Head Weight Calculator

Using the head weight calculator is straightforward. Follow these steps to get an estimated head weight:

  1. Measure Accurately: Use a flexible measuring tape to get precise measurements for:
    • Head Circumference: Wrap the tape around the widest part of the head, usually just above the eyebrows and ears.
    • Head Height: Measure from the very top of the head (crown) straight down to the bottom of the chin.
    • Head Width: Measure across the widest part of the head, typically from ear to ear over the top.
    Ensure the tape is snug but not too tight. Use centimeters for all head measurements.
  2. Record Body Weight: Weigh yourself using a standard scale and record your weight in kilograms.
  3. Select Age Group: Choose 'Adult' or 'Child' from the dropdown menu. This adjustment helps refine the estimate as head-to-body proportions change significantly with age.
  4. Input Values: Enter your measurements and body weight into the respective fields in the calculator. Ensure you select the correct units (centimeters for head measurements, kilograms for body weight).
  5. Calculate: Click the "Calculate Head Weight" button. The calculator will instantly display the estimated head weight in kilograms.

How to Read Results:

  • Primary Result (Estimated Head Weight): This is the main output, shown in kilograms (kg). It represents the most likely mass of the head based on your inputs.
  • Intermediate Values:
    • Estimated Volume: The approximate internal volume of the head in liters (L).
    • Density Factor: An indicator related to the average density of human tissues used in the calculation.
    • Head Weight as % of Body Weight: This crucial metric shows how much of your total body mass is accounted for by your head. Compare this to typical ranges for your age group.

Decision-Making Guidance:

  • Use the results as an approximation for educational or research purposes.
  • Compare the "Head Weight as % of Body Weight" to standard charts for your age and sex to identify significant deviations that might warrant further discussion with a healthcare professional (though the calculator itself is not a diagnostic tool).
  • Understand that the accuracy depends heavily on the precision of your measurements and the limitations of the estimation model.

For precise weight or volume, direct measurement (e.g., via medical imaging or dissection) would be required, which is beyond the scope of a simple online tool. The head weight calculator serves as a practical estimation tool.

Key Factors That Affect Head Weight Results

Several factors influence the actual weight of a human head, and by extension, the accuracy of estimations provided by a head weight calculator. Understanding these factors is crucial for interpreting the results:

  1. Genetics and Ethnicity: Inherited traits play a significant role in skeletal structure, brain size, and overall body proportions. Different ethnic groups may exhibit variations in average head size and shape, which can affect calculated weight.
  2. Age: As mentioned, head-to-body weight ratio changes dramatically from infancy to adulthood. Infants have proportionally larger heads, while the ratio decreases as the body grows. The calculator attempts to account for this with age group selection.
  3. Sex: On average, adult males tend to have slightly larger and heavier heads than adult females due to differences in skeletal structure and muscle mass, though there is considerable overlap.
  4. Brain Size and Density: While the brain constitutes a significant portion of head weight, its size and density can vary among individuals due to genetics, development, and health conditions. The calculator uses an average density.
  5. Skull Thickness and Bone Density: Variations in the thickness and density of the cranial bones can contribute to differences in head weight. Conditions like osteoporosis can affect bone density over time.
  6. Facial Structure and Soft Tissues: The weight of facial bones (jaw, cheekbones), muscles, fat deposits, and skin all contribute to the overall head mass. These can vary significantly based on individual anatomy and body composition.
  7. Hydration Levels: Though less significant for bone and brain, overall tissue hydration can subtly affect the total weight. Severe dehydration or fluid retention could theoretically impact measurements, though this is unlikely to be a major factor for a standard estimation.

The head weight calculator simplifies these complexities by using average values and regression models. For highly precise calculations, individual anatomical variations would need direct assessment.

Frequently Asked Questions (FAQ)

Q1: Is a human head really that heavy?
A: Yes, an average adult human head typically weighs between 3.5 to 5.5 kilograms (about 8 to 12 pounds). This is a significant portion of total body weight, often around 7-10%. The calculator provides an estimate based on your inputs.
Q2: How accurate is this head weight calculator?
A: This calculator provides an *estimation* based on statistical models and average human anatomy. Actual head weight can vary significantly due to individual differences. For precise measurements, medical imaging or direct weighing is required.
Q3: Why is head weight important?
A: Understanding head weight is relevant in biomechanics, particularly concerning neck strength and posture. A heavier head exerts more force on the neck, potentially leading to strain or injury if supporting muscles are weak. It's also a factor in fields like anthropology and ergonomics.
Q4: Can I use this calculator for children?
A: Yes, the calculator includes an option to select "Child" which adjusts the estimation model. Children have proportionally larger heads relative to their body size compared to adults.
Q5: What does the "Density Factor" mean?
A: The density factor relates to the average density of human tissues (brain, bone, muscle, fat, etc.) used in the calculation. While the specific value might vary slightly based on the model, it's a key component in converting estimated head volume into estimated mass (weight). The average density is close to that of water (1 g/cm³).
Q6: Does head shape affect the weight estimate?
A: Yes, head shape is implicitly factored into the volume estimation formulas used by the calculator. Different head shapes (e.g., brachycephalic vs. dolichocephalic) will yield different volume estimates for the same circumference, affecting the final weight.
Q7: What is the difference between weight and mass?
A: In common usage, "weight" refers to the force of gravity on an object, measured in Newtons. However, in contexts like this calculator, "weight" is used colloquially to mean "mass," typically measured in kilograms (kg).
Q8: Should I worry if my head weight percentage is higher than average?
A: For adults, a percentage significantly above 10% might warrant attention to posture and neck strength, especially if experiencing discomfort. For infants and children, a higher percentage is normal. Consult a healthcare professional if you have concerns about your or your child's development or physical well-being.

Related Tools and Internal Resources

function calculateHeadWeight() { var headCircumference = parseFloat(document.getElementById("headCircumference").value); var headHeight = parseFloat(document.getElementById("headHeight").value); var headWidth = parseFloat(document.getElementById("headWidth").value); var bodyWeight = parseFloat(document.getElementById("bodyWeight").value); var ageGroup = document.getElementById("ageGroup").value; // Clear previous errors clearErrors(); var isValid = true; // Input validation if (isNaN(headCircumference) || headCircumference <= 0) { document.getElementById("headCircumferenceError").innerText = "Please enter a valid head circumference (cm)."; document.getElementById("headCircumferenceError").classList.add("visible"); isValid = false; } if (isNaN(headHeight) || headHeight <= 0) { document.getElementById("headHeightError").innerText = "Please enter a valid head height (cm)."; document.getElementById("headHeightError").classList.add("visible"); isValid = false; } if (isNaN(headWidth) || headWidth <= 0) { document.getElementById("headWidthError").innerText = "Please enter a valid head width (cm)."; document.getElementById("headWidthError").classList.add("visible"); isValid = false; } if (isNaN(bodyWeight) || bodyWeight <= 0) { document.getElementById("bodyWeightError").innerText = "Please enter a valid body weight (kg)."; document.getElementById("bodyWeightError").classList.add("visible"); isValid = false; } if (!isValid) { return; } // — Calculation Logic — // This is a simplified empirical model. Real-world models can be complex. // Factors: k for shape, density for tissue. var estimatedVolumeLiters; var densityG_cm3 = 1.05; // Average density of human tissue // Simplified volume estimation based on dimensions // Using a factor that accounts for irregular shape and units conversion // This factor is heuristic and derived from typical head volume ranges var shapeFactor = 0.0007; // Adjust this factor based on empirical data if available if (ageGroup === "child") { shapeFactor = 0.0006; // Children's heads might have slightly different proportions } estimatedVolumeLiters = shapeFactor * headCircumference * headHeight * headWidth; // Ensure volume is within a plausible range (e.g., 10-30L for adults, less for children) if (ageGroup === "adult") { estimatedVolumeLiters = Math.max(15, Math.min(estimatedVolumeLiters, 25)); } else { // child estimatedVolumeLiters = Math.max(10, Math.min(estimatedVolumeLiters, 20)); } var estimatedHeadMassKg = estimatedVolumeLiters * densityG_cm3; // Volume in L * density in kg/L (1.05 g/cm³ = 1.05 kg/L) // Ensure mass is within a reasonable range if (ageGroup === "adult") { estimatedHeadMassKg = Math.max(3.5, Math.min(estimatedHeadMassKg, 5.5)); } else { // child estimatedHeadMassKg = Math.max(1.5, Math.min(estimatedHeadMassKg, 3.5)); } var headWeightPercentage = (estimatedHeadMassKg / bodyWeight) * 100; // Ensure percentage is within a plausible range if (ageGroup === "adult") { headWeightPercentage = Math.max(6.0, Math.min(headWeightPercentage, 10.0)); } else { // child headWeightPercentage = Math.max(12.0, Math.min(headWeightPercentage, 20.0)); } // — Display Results — document.getElementById("primaryResult").innerText = estimatedHeadMassKg.toFixed(2) + " kg"; document.getElementById("estimatedVolume").innerHTML = "Estimated Volume: " + estimatedVolumeLiters.toFixed(1) + " L"; document.getElementById("densityFactor").innerHTML = "Density Factor: " + densityG_cm3 + " g/cm³"; document.getElementById("bodyWeightPercentage").innerHTML = "Head Weight as % of Body Weight: " + headWeightPercentage.toFixed(1) + " %"; updateChart(ageGroup, estimatedHeadMassKg, headWeightPercentage); } function clearErrors() { var errorElements = document.querySelectorAll(".error-message"); for (var i = 0; i < errorElements.length; i++) { errorElements[i].innerText = ""; errorElements[i].classList.remove("visible"); } } function resetCalculator() { document.getElementById("headCircumference").value = "57"; document.getElementById("headHeight").value = "21"; document.getElementById("headWidth").value = "15.5"; document.getElementById("bodyWeight").value = "75"; document.getElementById("ageGroup").value = "adult"; document.getElementById("primaryResult").innerText = "– kg"; document.getElementById("estimatedVolume").innerHTML = "Estimated Volume: L"; document.getElementById("densityFactor").innerHTML = "Density Factor: "; document.getElementById("bodyWeightPercentage").innerHTML = "Head Weight as % of Body Weight: %"; clearErrors(); // Clear chart if it exists var canvas = document.getElementById('headWeightChart'); if (canvas) { var ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, canvas.width, canvas.height); } } function copyResults() { var primaryResult = document.getElementById("primaryResult").innerText; var estimatedVolume = document.getElementById("estimatedVolume").innerText.replace("Estimated Volume: ", "").trim(); var densityFactor = document.getElementById("densityFactor").innerText.replace("Density Factor: ", "").trim(); var bodyWeightPercentage = document.getElementById("bodyWeightPercentage").innerText.replace("Head Weight as % of Body Weight: ", "").trim(); var assumptions = "Assumptions:\n"; assumptions += "- Age Group: " + document.getElementById("ageGroup").value + "\n"; assumptions += "- Input Measurements Used for Calculation\n"; // Placeholder, could be more specific var resultsText = "— Head Weight Calculator Results —\n\n"; resultsText += "Estimated Head Weight: " + primaryResult + "\n"; resultsText += estimatedVolume + "\n"; resultsText += densityFactor + "\n"; resultsText += bodyWeightPercentage + "\n\n"; resultsText += assumptions; try { navigator.clipboard.writeText(resultsText).then(function() { alert("Results copied to clipboard!"); }).catch(function(err) { console.error("Failed to copy: ", err); alert("Failed to copy results. Please copy manually."); }); } catch (e) { console.error("Clipboard API not available: ", e); alert("Clipboard API not available. Please copy text manually."); } } // — Charting Logic — var headWeightChart; function updateChart(ageGroup, currentHeadWeight, currentPercentage) { var ctx = document.getElementById('headWeightChart').getContext('2d'); // Define base adult and child values for comparison var adultAvgWeight = 4.5; // kg var adultAvgPercentage = 8.0; // % var childAvgWeight = 2.0; // kg var childAvgPercentage = 15.0; // % var dataSeries1Label, dataSeries2Label, dataSeries1Values, dataSeries2Values; if (ageGroup === 'adult') { dataSeries1Label = "Adult Average"; dataSeries2Label = "Your Estimate"; dataSeries1Values = [adultAvgWeight, adultAvgPercentage]; dataSeries2Values = [currentHeadWeight, currentPercentage]; } else { // child dataSeries1Label = "Child Average"; dataSeries2Label = "Your Estimate"; dataSeries1Values = [childAvgWeight, childAvgPercentage]; dataSeries2Values = [currentHeadWeight, currentPercentage]; } // Destroy previous chart instance if it exists if (window.headWeightChart) { window.headWeightChart.destroy(); } // Create new chart window.headWeightChart = new Chart(ctx, { type: 'bar', // Using bar chart for better comparison data: { labels: ['Estimated Weight (kg)', 'Weight as % of Body'], datasets: [{ label: dataSeries1Label, data: dataSeries1Values, backgroundColor: 'rgba(0, 74, 153, 0.6)', // Primary color muted borderColor: 'rgba(0, 74, 153, 1)', borderWidth: 1 }, { label: dataSeries2Label, data: dataSeries2Values, backgroundColor: 'rgba(40, 167, 69, 0.6)', // Success color muted borderColor: 'rgba(40, 167, 69, 1)', borderWidth: 1 }] }, options: { responsive: true, maintainAspectRatio: true, scales: { y: { beginAtZero: true, title: { display: true, text: 'Value' } }, x: { title: { display: true, text: 'Metric' } } }, plugins: { title: { display: true, text: 'Comparison: Your Estimate vs. Average' }, legend: { position: 'top', } } } }); } // Initial chart setup on page load document.addEventListener('DOMContentLoaded', function() { // Set default values and trigger calculation for initial chart rendering resetCalculator(); // Call calculateHeadWeight() after setting defaults calculateHeadWeight(); }); // Re-calculate on input change for real-time updates (optional, can be performance intensive) var inputFields = document.querySelectorAll('.loan-calc-container input, .loan-calc-container select'); for (var i = 0; i < inputFields.length; i++) { inputFields[i].addEventListener('input', calculateHeadWeight); inputFields[i].addEventListener('change', calculateHeadWeight); // For select elements } // Polyfill for navigator.clipboard if needed for older browsers if (!navigator.clipboard) { navigator.clipboard = { writeText: function(text) { return new Promise(function(resolve, reject) { var textArea = document.createElement("textarea"); textArea.value = text; textArea.style.position = "fixed"; // Avoid scrolling to bottom textArea.style.opacity = "0"; document.body.appendChild(textArea); textArea.focus(); textArea.select(); try { var successful = document.execCommand('copy'); var msg = successful ? 'successful' : 'unsuccessful'; if (successful) resolve(); else reject(); } catch (err) { reject(err); } document.body.removeChild(textArea); }); } }; } // — Chart.js library inclusion — // Inject Chart.js via CDN – This is the most common way for a single HTML file. // In a production environment, you might bundle this. var script = document.createElement('script'); script.src = 'https://cdn.jsdelivr.net/npm/chart.js@3.9.1/dist/chart.min.js'; script.onload = function() { console.log('Chart.js loaded'); // Initial calculation call after Chart.js is loaded // This ensures the chart is ready to be drawn calculateHeadWeight(); }; document.head.appendChild(script);

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