Calculate Goal Bmi Weight

Calculate Goal BMI Weight: Your Personalized Health Target body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; line-height: 1.6; margin: 0; padding: 0; background-color: #f8f9fa; color: #333; } .container { max-width: 1000px; margin: 20px auto; padding: 25px; background-color: #fff; border-radius: 8px; box-shadow: 0 4px 15px rgba(0, 74, 153, 0.1); display: flex; flex-direction: column; align-items: center; } header { width: 100%; background-color: #004a99; color: #fff; padding: 20px 0; text-align: center; border-radius: 8px 8px 0 0; } header h1 { margin: 0; font-size: 2.2em; font-weight: 600; } main { width: 100%; padding: 25px 20px; } h2, h3 { color: #004a99; margin-top: 1.5em; } .calculator-section { width: 100%; display: flex; flex-direction: column; align-items: center; margin-bottom: 30px; padding: 20px; border: 1px solid #e0e0e0; border-radius: 8px; background-color: #fdfdfd; } .loan-calc-container { width: 100%; max-width: 600px; display: flex; flex-direction: column; gap: 20px; } .input-group { display: flex; flex-direction: column; } .input-group label { margin-bottom: 8px; font-weight: 500; color: #004a99; } .input-group input, .input-group select { padding: 12px 15px; border: 1px solid #ccc; border-radius: 4px; font-size: 1em; transition: border-color 0.3s ease; } .input-group input:focus, .input-group select:focus { outline: none; border-color: #004a99; box-shadow: 0 0 0 3px rgba(0, 74, 153, 0.2); } .input-group .helper-text { font-size: 0.85em; color: #666; margin-top: 5px; } .error-message { color: #dc3545; font-size: 0.9em; margin-top: 5px; min-height: 1.2em; } .button-group { display: flex; gap: 15px; justify-content: center; margin-top: 25px; } button { padding: 12px 25px; border: none; border-radius: 5px; cursor: pointer; font-size: 1em; font-weight: 500; transition: background-color 0.3s ease, transform 0.2s ease; } .btn-primary { background-color: #004a99; color: white; } .btn-primary:hover { background-color: #003a7a; transform: translateY(-2px); } .btn-secondary { background-color: #6c757d; color: white; } .btn-secondary:hover { background-color: #5a6268; transform: translateY(-2px); } .btn-copy { background-color: #28a745; color: white; } .btn-copy:hover { background-color: #218838; transform: translateY(-2px); } .results-section { width: 100%; display: flex; flex-direction: column; align-items: center; margin-top: 30px; padding: 20px; border: 1px solid #e0e0e0; border-radius: 8px; background-color: #f0f8ff; } .main-result { font-size: 2.5em; font-weight: bold; color: #28a745; margin: 15px 0; padding: 15px 25px; background-color: #e8f5e9; border-radius: 8px; border: 2px solid #28a745; } .intermediate-results { display: flex; flex-wrap: wrap; justify-content: center; gap: 20px; margin-top: 20px; padding: 15px; background-color: #e3f2fd; border-radius: 8px; width: 100%; } .intermediate-value { text-align: center; padding: 10px 15px; background-color: #bbdefb; border-radius: 5px; min-width: 120px; } .intermediate-value strong { display: block; font-size: 1.2em; color: #004a99; } .formula-explanation { text-align: center; font-size: 0.95em; color: #555; margin-top: 20px; padding: 10px; background-color: #fff; border-radius: 5px; border-left: 4px solid #004a99; } table { width: 100%; border-collapse: collapse; margin-top: 30px; box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05); } caption { font-size: 1.1em; font-weight: bold; color: #004a99; margin-bottom: 15px; text-align: left; } th, td { padding: 12px 15px; text-align: left; border: 1px solid #ddd; } thead th { background-color: #004a99; color: white; font-weight: 500; } tbody tr:nth-child(even) { background-color: #f2f2f2; } canvas { display: block; margin: 30px auto; max-width: 100%; background-color: #fff; border-radius: 8px; box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05); } .article-content { width: 100%; margin-top: 40px; padding: 20px; background-color: #fff; border-radius: 8px; box-shadow: 0 4px 15px rgba(0, 74, 153, 0.1); } .article-content p, .article-content ul, .article-content ol { margin-bottom: 1.2em; } .article-content ul, .article-content ol { padding-left: 25px; } .article-content li { margin-bottom: 0.8em; } .article-content h2, .article-content h3 { margin-top: 1.8em; margin-bottom: 0.8em; border-bottom: 1px solid #eee; padding-bottom: 5px; } .article-content a { color: #004a99; text-decoration: none; } .article-content a:hover { text-decoration: underline; } .internal-links-list { list-style: none; padding: 0; } .internal-links-list li { margin-bottom: 15px; padding: 10px; border: 1px solid #e0e0e0; border-radius: 5px; background-color: #f9f9f9; } .internal-links-list strong { color: #004a99; } @media (max-width: 768px) { .container { margin: 10px; padding: 15px; } header h1 { font-size: 1.8em; } .main-result { font-size: 2em; } .intermediate-results { flex-direction: column; align-items: center; } .button-group { flex-direction: column; align-items: center; } button { width: 80%; } }

Calculate Goal BMI Weight

BMI Goal Weight Calculator

Enter your height in centimeters.
Underweight (18.5) Healthy Weight (18.5 – 24.9) Overweight (25 – 29.9) Obese Class I (30 – 34.9) Obese Class II (35 – 39.9) Obese Class III (40+)
Select your target BMI range.

Your Goal Weight Calculation

Height cm
Target BMI
Min Healthy Weight kg
Max Healthy Weight kg
Formula: Goal Weight (kg) = BMI x (Height in meters)²
We calculate a target weight within your chosen BMI category. For the "Healthy Weight" category, we use the midpoint of the range (21.75) for the primary goal weight.

BMI Weight Ranges by Height

Weight Ranges for Your Height (kg)
BMI Category BMI Range Lower Weight Goal Upper Weight Goal
Underweight < 18.5
Healthy Weight 18.5 – 24.9
Overweight 25 – 29.9
Obese Class I 30 – 34.9
Obese Class II 35 – 39.9
Obese Class III ≥ 40

BMI vs. Weight Chart

Visualizing weight ranges across different BMI categories for your height.

Calculate Goal BMI Weight: Your Personalized Health Target

Understanding and achieving a healthy weight is a cornerstone of overall well-being. The Body Mass Index (BMI) is a widely used metric to gauge weight status in relation to height. Our calculate goal BMI weight tool empowers you to set specific, achievable weight targets aligned with established health categories. This detailed guide will walk you through what BMI is, how to calculate your goal weight, and factors that influence your journey.

What is {primary_keyword}?

{primary_keyword} refers to determining a specific weight target that corresponds to a desirable Body Mass Index (BMI) for an individual, based on their height. BMI is a simple index of weight-for-height and is calculated as weight in kilograms divided by the square of height in meters (kg/m²).

Who should use it: Anyone looking to understand a healthy weight range for their height, set realistic weight loss or gain goals, or simply gain insight into their current weight status. It's particularly useful for individuals before starting a new diet or exercise program, or those seeking to improve their overall health.

Common misconceptions:

  • BMI is a perfect measure of health: BMI does not directly measure body fat percentage or differentiate between muscle mass and fat mass. A very muscular person might have a high BMI but be healthy.
  • BMI determines your exact ideal weight: BMI provides a range. Your individual ideal weight can vary based on body composition, age, sex, and other factors.
  • BMI is the only factor for health: While important, BMI is just one piece of the puzzle. Diet, exercise, sleep, stress levels, and genetics all play significant roles.

{primary_keyword} Formula and Mathematical Explanation

The core of calculating a goal BMI weight lies in rearranging the BMI formula. The standard BMI formula is:

BMI = Weight (kg) / (Height (m))²

To find the goal weight, we rearrange this formula:

Goal Weight (kg) = Desired BMI x (Height (m))²

Let's break down the variables:

BMI Calculation Variables
Variable Meaning Unit Typical Range / Notes
Height (m) Individual's height converted to meters. Meters (m) e.g., 1.70m for 170cm.
Height (cm) Individual's height in centimeters. Centimeters (cm) Used as primary input for convenience.
Desired BMI The target Body Mass Index value. kg/m² Ranges from < 18.5 (Underweight) to ≥ 40 (Obese Class III).
Goal Weight (kg) The calculated target weight in kilograms. Kilograms (kg) The output of our calculation.
Min Healthy Weight Lower bound of the healthy weight range for the user's height. Kilograms (kg) Calculated using BMI 18.5.
Max Healthy Weight Upper bound of the healthy weight range for the user's height. Kilograms (kg) Calculated using BMI 24.9.

The calculator first converts your height from centimeters to meters by dividing by 100. Then, it squares this value. Finally, it multiplies the squared height by your selected desired BMI to arrive at your goal weight in kilograms.

Practical Examples (Real-World Use Cases)

Example 1: Setting a Healthy Weight Goal

Scenario: Sarah is 165 cm tall and wants to achieve a weight within the healthy BMI range (18.5 – 24.9). She decides to aim for a BMI of 22, which falls comfortably within this range.

  • Inputs:
  • Height: 165 cm
  • Desired BMI Category: Healthy Weight (we'll use the midpoint BMI of 21.75 for calculation, or a specific target like 22)

Calculation:

  • Height in meters = 165 cm / 100 = 1.65 m
  • Height squared = (1.65 m)² = 2.7225 m²
  • Goal Weight = 21.75 (midpoint BMI) x 2.7225 m² = 59.23 kg
  • (If targeting BMI 22: 22 x 2.7225 = 59.90 kg)
  • Min Healthy Weight (BMI 18.5): 18.5 x 2.7225 = 50.37 kg
  • Max Healthy Weight (BMI 24.9): 24.9 x 2.7225 = 67.79 kg

Interpretation: Sarah's goal weight, aiming for the middle of the healthy BMI range, is approximately 59.23 kg. This falls perfectly within her healthy weight range of 50.37 kg to 67.79 kg. This gives her a clear target and a defined range to work towards.

Example 2: Understanding Overweight BMI

Scenario: David is 180 cm tall and currently has a BMI in the overweight category. He wants to understand what weight would put him in the lower end of the overweight category (BMI 25).

  • Inputs:
  • Height: 180 cm
  • Desired BMI Category: Overweight (we will calculate for BMI 25)

Calculation:

  • Height in meters = 180 cm / 100 = 1.80 m
  • Height squared = (1.80 m)² = 3.24 m²
  • Goal Weight (at BMI 25) = 25 x 3.24 m² = 81.00 kg
  • Max Overweight Weight (BMI 29.9): 29.9 x 3.24 = 96.88 kg

Interpretation: David's goal weight to be at the threshold of the overweight category is 81.00 kg. This gives him a concrete target to aim for to move out of the overweight classification and towards a healthier weight range. He can also see that staying below 96.88 kg is important to avoid entering the obese category.

How to Use This {primary_keyword} Calculator

  1. Enter Your Height: Input your current height in centimeters into the 'Height (cm)' field.
  2. Select Your Target BMI Category: Choose the BMI category you aim to achieve from the dropdown menu. Options range from Underweight to Obese Class III, with a specific focus on the Healthy Weight range (18.5 – 24.9). If you select "Healthy Weight," the calculator uses the midpoint (21.75) for the primary "Goal Weight" display but shows the full range in the table.
  3. Click Calculate: Press the 'Calculate Goal Weight' button.

How to read results:

  • Goal Weight: This is your primary target weight in kilograms, calculated based on your height and the midpoint BMI of your selected category (or the specific BMI value if provided).
  • Height & Target BMI: Confirms the inputs used for the calculation.
  • Min/Max Healthy Weight: Shows the weight range (in kg) that corresponds to a BMI of 18.5 to 24.9 for your height.
  • Weight Ranges Table: Provides a comprehensive view of different weight targets across various BMI categories for your specific height.
  • Chart: Visually represents these weight ranges.

Decision-making guidance: Use the 'Goal Weight' as your primary target. The 'Min Healthy Weight' and 'Max Healthy Weight' indicate the optimal range for long-term health. If your current weight is significantly outside these ranges, consult with a healthcare professional or a registered dietitian to create a safe and effective plan. The 'Reset' button clears all fields, and 'Copy Results' allows you to save your findings.

Key Factors That Affect {primary_keyword} Results

While the BMI calculation is straightforward, achieving and maintaining a goal weight is influenced by numerous factors:

  1. Body Composition: Muscle is denser than fat. Individuals with higher muscle mass may have a higher BMI but a lower body fat percentage, indicating better health than someone with the same BMI but more fat.
  2. Age: Metabolism tends to slow down with age, which can affect how easily weight is gained or lost. Body composition also changes over time.
  3. Sex: Biological differences in body composition (e.g., average muscle mass, fat distribution) can influence ideal weight ranges.
  4. Genetics: Your genetic makeup can play a role in your metabolism, appetite regulation, and where your body stores fat.
  5. Activity Level: A higher level of physical activity increases muscle mass and calorie expenditure, potentially altering the "ideal" weight for a given BMI.
  6. Dietary Habits: Calorie intake, nutrient density, and meal timing significantly impact weight management and overall health, independent of BMI.
  7. Medical Conditions & Medications: Certain health issues (like thyroid problems) and medications can affect metabolism and weight.
  8. Skeletal Frame Size: While less scientifically rigorous, some believe bone structure can influence perceived healthy weight.

Frequently Asked Questions (FAQ)

Q1: Is BMI the best indicator of health?
A1: BMI is a useful screening tool, but it's not a perfect measure of health. It doesn't account for body composition (muscle vs. fat). Other factors like waist circumference, blood pressure, cholesterol levels, and fitness levels are also crucial.
Q2: Can I have a healthy BMI but be unhealthy?
A2: Yes. This is often referred to as "thin outside, fat inside" (TOFI) or "metabolically obese normal weight" (MONW). It means having a healthy BMI but high body fat percentage and potentially poor metabolic health markers.
Q3: Can I have an unhealthy BMI but be healthy?
A3: Yes, particularly muscular individuals. Athletes or those with significant muscle mass might have a BMI in the overweight or even obese category due to muscle density, despite having low body fat and good cardiovascular health.
Q4: What should my goal weight be if I'm very muscular?
A4: If you are very muscular, BMI might be less relevant. Focus more on body fat percentage, waist circumference, and overall fitness. Consult a healthcare professional or certified trainer for personalized advice.
Q5: How quickly should I aim to reach my goal weight?
A5: Sustainable weight loss is typically recommended at 1-2 pounds (0.5-1 kg) per week. Rapid weight loss can be unhealthy and is often not sustainable. Focus on gradual lifestyle changes.
Q6: Does this calculator account for body fat percentage?
A6: No, this calculator is based solely on the standard BMI formula, which does not measure body fat percentage. It provides a general guideline based on weight and height.
Q7: What if my goal weight falls outside the "Healthy Weight" range calculated?
A7: If your desired goal weight falls outside the calculated healthy range (e.g., you aim for a higher BMI due to medical reasons or athletic build, or a lower BMI for specific athletic performance), it's essential to discuss this with a healthcare provider. BMI ranges are general guidelines.
Q8: Can I use this calculator for children?
A8: No, this calculator is designed for adults. BMI calculations and healthy weight ranges for children and adolescents are different and require specialized growth charts and interpretations by healthcare professionals.

Related Tools and Internal Resources

function calculateBmiGoalWeight() { var heightCmInput = document.getElementById("heightCm"); var bmiCategorySelect = document.getElementById("bmiCategory"); var heightCmError = document.getElementById("heightCmError"); var goalWeightResult = document.getElementById("goalWeightResult"); var displayHeightCm = document.getElementById("displayHeightCm"); var displayBmiCategory = document.getElementById("displayBmiCategory"); var minHealthyWeight = document.getElementById("minHealthyWeight"); var maxHealthyWeight = document.getElementById("maxHealthyWeight"); // Clear previous errors heightCmError.textContent = ""; var heightCm = parseFloat(heightCmInput.value); var bmiCategoryValue = parseFloat(bmiCategorySelect.value); var bmiCategoryLabel = bmiCategorySelect.options[bmiCategorySelect.selectedIndex].text.split(' ')[0]; // Extract category name // — Input Validation — if (isNaN(heightCm) || heightCm <= 0) { heightCmError.textContent = "Please enter a valid height in centimeters."; return; } if (heightCm 250) { heightCmError.textContent = "Height seems unrealistic. Please enter a value between 50 and 250 cm."; return; } // — Calculations — var heightM = heightCm / 100; var heightMSquared = heightM * heightM; // Specific BMI values for ranges var bmiValues = { 18.5: "Underweight", 21.75: "Healthy Weight", // Midpoint for calculation when selected 27.4: "Overweight", // Midpoint for calculation 35: "Obese Class I", // Midpoint for calculation 40: "Obese Class II", // Midpoint for calculation 50: "Obese Class III" // Representative high BMI for calculation }; var targetBmiForCalc; var selectedBmiLabel = bmiCategorySelect.options[bmiCategorySelect.selectedIndex].text; if (selectedBmiLabel.includes("Healthy Weight")) { targetBmiForCalc = 21.75; // Midpoint of 18.5-24.9 } else if (selectedBmiLabel.includes("Underweight")) { targetBmiForCalc = 18.5; } else if (selectedBmiLabel.includes("Overweight")) { targetBmiForCalc = 27.4; // Midpoint of 25-29.9 } else if (selectedBmiLabel.includes("Obese Class I")) { targetBmiForCalc = 32.45; // Midpoint of 30-34.9 } else if (selectedBmiLabel.includes("Obese Class II")) { targetBmiForCalc = 37.45; // Midpoint of 35-39.9 } else if (selectedBmiLabel.includes("Obese Class III")) { targetBmiForCalc = 40; // Lower bound of this category } else { targetBmiForCalc = bmiCategoryValue; // Fallback } var goalWeight = targetBmiForCalc * heightMSquared; var minHealthyWeightCalc = 18.5 * heightMSquared; var maxHealthyWeightCalc = 24.9 * heightMSquared; // — Update Results — goalWeightResult.textContent = goalWeight.toFixed(2); displayHeightCm.textContent = heightCm.toFixed(0); displayBmiCategory.textContent = bmiCategoryValue.toFixed(1); // Display the selected value from dropdown minHealthyWeight.textContent = minHealthyWeightCalc.toFixed(2); maxHealthyWeight.textContent = maxHealthyWeightCalc.toFixed(2); // — Update Table — document.getElementById("tableUnderweightLower").textContent = (18.5 * heightMSquared).toFixed(2); document.getElementById("tableUnderweightUpper").textContent = (heightMSquared * 24.9).toFixed(2); // Using 24.9 as the upper end of healthy document.getElementById("tableHealthyLower").textContent = (18.5 * heightMSquared).toFixed(2); document.getElementById("tableHealthyUpper").textContent = (24.9 * heightMSquared).toFixed(2); document.getElementById("tableOverweightLower").textContent = (25 * heightMSquared).toFixed(2); document.getElementById("tableOverweightUpper").textContent = (29.9 * heightMSquared).toFixed(2); document.getElementById("tableObese1Lower").textContent = (30 * heightMSquared).toFixed(2); document.getElementById("tableObese1Upper").textContent = (34.9 * heightMSquared).toFixed(2); document.getElementById("tableObese2Lower").textContent = (35 * heightMSquared).toFixed(2); document.getElementById("tableObese2Upper").textContent = (39.9 * heightMSquared).toFixed(2); document.getElementById("tableObese3Lower").textContent = (40 * heightMSquared).toFixed(2); document.getElementById("tableObese3Upper").textContent = "–"; // No upper limit defined for Class III // Update chart updateBmiWeightChart(heightMSquared); } function resetCalculator() { document.getElementById("heightCm").value = ""; document.getElementById("bmiCategory").value = "21.75"; // Default to Healthy Weight midpoint document.getElementById("heightCmError").textContent = ""; document.getElementById("goalWeightResult").textContent = "–"; document.getElementById("displayHeightCm").textContent = "–"; document.getElementById("displayBmiCategory").textContent = "–"; document.getElementById("minHealthyWeight").textContent = "–"; document.getElementById("maxHealthyWeight").textContent = "–"; var tableCells = document.querySelectorAll('#bmiWeightTable tbody td'); for (var i = 0; i < tableCells.length; i++) { if (tableCells[i].id.includes("Lower") || tableCells[i].id.includes("Upper")) { tableCells[i].textContent = "–"; } } // Clear canvas var canvas = document.getElementById('bmiWeightChart'); var ctx = canvas.getContext('2d'); ctx.clearRect(0, 0, canvas.width, canvas.height); } function copyResults() { var mainResult = document.getElementById("goalWeightResult").textContent; var height = document.getElementById("displayHeightCm").textContent; var targetBmi = document.getElementById("displayBmiCategory").textContent; var minHealthy = document.getElementById("minHealthyWeight").textContent; var maxHealthy = document.getElementById("maxHealthyWeight").textContent; if (mainResult === "–") { alert("No results to copy yet."); return; } var assumptions = "Assumptions:\n"; assumptions += "- Height: " + height + " cm\n"; assumptions += "- Target BMI: " + targetBmi + "\n"; assumptions += "- Calculated Goal Weight: " + mainResult + " kg\n"; assumptions += "- Min Healthy Weight (BMI 18.5-24.9): " + minHealthy + " kg – " + maxHealthy + " kg\n"; var textToCopy = "— BMI Goal Weight Calculation —\n\n" + assumptions; navigator.clipboard.writeText(textToCopy).then(function() { alert("Results copied to clipboard!"); }).catch(function(err) { console.error('Failed to copy: ', err); alert("Failed to copy results. Please copy manually."); }); } // — Charting — var bmiChartInstance = null; // To hold the chart instance function updateBmiWeightChart(heightMSquared) { var canvas = document.getElementById('bmiWeightChart'); var ctx = canvas.getContext('2d'); // Destroy previous chart instance if it exists if (bmiChartInstance) { bmiChartInstance.destroy(); } // Define BMI categories and their typical ranges var bmiDataSeries = [ { label: "Underweight", range: [0, 18.5], color: '#ffc107' }, // Yellow { label: "Healthy Weight", range: [18.5, 24.9], color: '#28a745' }, // Green { label: "Overweight", range: [25, 29.9], color: '#ffc107' }, // Yellow { label: "Obese I", range: [30, 34.9], color: '#fd7e14' }, // Orange { label: "Obese II", range: [35, 39.9], color: '#dc3545' }, // Red { label: "Obese III", range: [40, 60], color: '#6f42c1' } // Purple (arbitrary upper limit for visual) ]; var chartLabels = []; var chartDataLower = []; var chartDataUpper = []; var backgroundColors = []; var borderColors = []; bmiDataSeries.forEach(function(series) { var lowerWeight = series.range[0] * heightMSquared; var upperWeight = series.range[1] * heightMSquared; chartLabels.push(series.label + " (" + series.range[0] + "-" + series.range[1] + ")"); chartDataLower.push(lowerWeight); chartDataUpper.push(upperWeight); backgroundColors.push(hexToRgba(series.color, 0.6)); // Use RGBA for transparency borderColors.push(series.color); }); // Adjust the first series' lower bound to be 0 if it starts at 18.5 if (bmiDataSeries[0].range[0] === 0) { chartDataLower[0] = 0; chartDataUpper[0] = bmiDataSeries[0].range[1] * heightMSquared; } bmiChartInstance = new Chart(ctx, { type: 'bar', // Using bar chart to represent ranges data: { labels: chartLabels, datasets: [ { label: 'Lower Weight Goal (kg)', data: chartDataLower, backgroundColor: backgroundColors, borderColor: borderColors, borderWidth: 1, order: 2 // Render lower bounds first }, { label: 'Upper Weight Goal (kg)', data: chartDataUpper, backgroundColor: backgroundColors.map(function(color) { return hexToRgba(color, 0.2); }), // Lighter fill for upper range visual borderColor: borderColors, borderWidth: 1, order: 1 // Render upper bounds after lower bounds } ] }, options: { responsive: true, maintainAspectRatio: true, scales: { y: { beginAtZero: true, title: { display: true, text: 'Weight (kg)' } }, x: { title: { display: true, text: 'BMI Category' } } }, plugins: { title: { display: true, text: 'Weight Ranges for Your Height (kg)', font: { size: 16 } }, legend: { display: true, position: 'top', } }, tooltips: { // Deprecated, use 'plugins.tooltip' enabled: true }, hover: { mode: 'nearest', intersect: true }, animation: { duration: 500, easing: 'easeOutQuad' } } }); } // Helper function to convert hex to RGBA function hexToRgba(hex, alpha) { var r = parseInt(hex.slice(1, 3), 16); var g = parseInt(hex.slice(3, 5), 16); var b = parseInt(hex.slice(5, 7), 16); return 'rgba(' + r + ',' + g + ',' + b + ',' + alpha + ')'; } // Initial chart rendering on load if inputs are present (optional, but good for pre-filled forms) document.addEventListener('DOMContentLoaded', function() { // Trigger initial calculation if default values are set or if you want it to run on page load // For this calculator, we'll wait for user input, but you could call calculateBmiGoalWeight() here if needed // Add event listeners for real-time updates document.getElementById('heightCm').addEventListener('input', function() { // Basic validation for immediate feedback var heightCm = parseFloat(this.value); var heightCmError = document.getElementById("heightCmError"); if (isNaN(heightCm) || heightCm 250) { heightCmError.textContent = "Enter height in cm (e.g., 170)."; } else { heightCmError.textContent = ""; calculateBmiGoalWeight(); // Recalculate } }); document.getElementById('bmiCategory').addEventListener('change', function() { calculateBmiGoalWeight(); // Recalculate }); // Initial chart setup (without data, will be populated on first calculation) var canvas = document.getElementById('bmiWeightChart'); var ctx = canvas.getContext('2d'); // Initialize with empty state or placeholder bmiChartInstance = new Chart(ctx, { type: 'bar', data: { labels: [], datasets: [] }, options: { responsive: true, maintainAspectRatio: true, scales: { y: { beginAtZero: true, title: { display: true, text: 'Weight (kg)' } }, x: { title: { display: true, text: 'BMI Category' } } }, plugins: { title: { display: true, text: 'Weight Ranges for Your Height (kg)', font: { size: 16 } }, legend: { display: true, position: 'top' } } } }); });

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