Your estimated ideal weight range, calculated based on your height.
— kg
BMI: —
Lower Ideal Weight: — kg
Upper Ideal Weight: — kg
Formula: Varies by standard (e.g., BMI-based for adults).
Results copied to clipboard!
Enter your height in centimeters.
Enter your age (affects some formulas, typically 18-65).
Male
Female
Select your gender for more accurate estimations.
This calculator provides an estimated ideal weight range. Factors like muscle mass, bone density, and body composition can influence individual needs.
Ideal Weight Range vs. BMI Categories for Your Height
Ideal Weight Ranges by Height (General Adult)**
Height (cm)
Min Ideal Weight (kg)
Max Ideal Weight (kg)
Healthy BMI Range
150
44.1
59.4
18.5 – 24.9
155
47.6
64.1
18.5 – 24.9
160
51.2
68.8
18.5 – 24.9
165
54.9
73.7
18.5 – 24.9
170
58.6
78.7
18.5 – 24.9
175
62.5
83.8
18.5 – 24.9
180
66.5
89.0
18.5 – 24.9
185
70.6
94.3
18.5 – 24.9
190
74.8
99.7
18.5 – 24.9
**Note: These are generalized ranges. Consult a healthcare professional for personalized advice.
What is Ideal Weight in kg and cm?
The concept of "ideal weight" refers to a body weight that is considered healthiest for a person's height, sex, and age. It's not a single, rigid number but rather a range that suggests a lower risk for weight-related health problems like heart disease, diabetes, and certain cancers. Using measurements in kilograms (kg) for weight and centimeters (cm) for height allows for precise calculations using established health metrics. Understanding your ideal weight in kg and cm is a crucial step towards maintaining a healthy lifestyle and preventing chronic diseases. It helps individuals set realistic weight goals and monitor their progress effectively. Many people use this metric as a starting point for fitness journeys or health assessments.
Who should use an ideal weight calculator? Anyone looking to understand their current weight in relation to their height should find this tool beneficial. This includes individuals seeking to lose weight, gain weight healthily, or simply maintain a weight that supports optimal health. Athletes, fitness enthusiasts, and those with specific health concerns may also use it, though it's important to remember that specialized needs might require professional consultation. It's particularly useful for adults within a typical age range where growth has ceased.
Common misconceptions about ideal weight include the belief that it's purely about aesthetics or that there's one perfect number for everyone. In reality, ideal weight is a health indicator, and body composition (muscle vs. fat) plays a significant role. A muscular individual might weigh more than the "ideal" range suggests but still be very healthy. Another misconception is that ideal weight formulas are infallible; they are estimations and should be used as guides, not strict rules. The focus should always be on overall health, energy levels, and well-being, not just hitting a number.
Ideal Weight Calculator Formula and Mathematical Explanation
Calculating ideal weight is not based on a single, universally accepted formula, especially when considering nuanced individual factors. However, the most common and widely recognized method for adults relies on the Body Mass Index (BMI). BMI is a simple index of weight-for-height and is calculated as weight in kilograms divided by the square of height in meters. For practical use with centimeters, we adjust the formula.
The healthy BMI range is generally considered to be between 18.5 and 24.9. Using this range, we can calculate a corresponding ideal weight range for a given height.
Core Calculation (BMI-Based Range):
1. Convert Height to Meters: Divide height in centimeters by 100.
Height (m) = Height (cm) / 100
2. Calculate Lower Ideal Weight: Use the lower bound of the healthy BMI (18.5).
Lower Ideal Weight (kg) = 18.5 * (Height (m))^2
3. Calculate Upper Ideal Weight: Use the upper bound of the healthy BMI (24.9).
Upper Ideal Weight (kg) = 24.9 * (Height (m))^2
For specific, sometimes simpler, formulas like the Devine or Robinson formulas, different multipliers are used, often incorporating sex and sometimes age. However, the BMI-based range is more representative of a healthy spectrum.
Variables Table:
Variables Used in Ideal Weight Calculation
Variable
Meaning
Unit
Typical Range/Value
Height (cm)
The vertical distance from the sole of the foot to the top of the head.
Centimeters (cm)
140 – 200 cm (adults)
Height (m)
Height converted to meters for BMI calculation.
Meters (m)
1.4 – 2.0 m
Age
The number of years a person has lived.
Years
18 – 65 (for standard adult formulas)
Gender
Biological sex, often used in specific formulas.
Categorical
Male, Female
BMI Lower Bound
The minimum BMI value considered healthy.
Unitless
18.5
BMI Upper Bound
The maximum BMI value considered healthy.
Unitless
24.9
Ideal Weight (kg)
Calculated weight considered healthy for the given height.
Kilograms (kg)
Varies based on height
Practical Examples (Real-World Use Cases)
Understanding ideal weight is more than just numbers; it's about applying these calculations to real life. Here are a couple of examples illustrating how individuals might use an ideal weight calculator in kg and cm.
Example 1: Sarah, aiming for a healthier weight
Sarah is 30 years old, female, and measures 165 cm in height. She feels she is carrying a few extra pounds and wants to understand what a healthy weight range looks like for her.
Inputs: Height = 165 cm, Age = 30, Gender = Female.
Ideal Weight Range: Approximately 50.4 kg to 67.8 kg.
Current BMI (if known): Let's assume Sarah currently weighs 72 kg. Her BMI would be 72 / (1.65)^2 ≈ 26.4, placing her in the overweight category.
Interpretation: Sarah's current weight of 72 kg is slightly above the healthy range. To reach the upper end of her ideal weight, she would need to lose about 4.2 kg. Aiming for a weight around 60-65 kg could put her well within the healthy BMI. This information empowers Sarah to set a realistic weight loss goal and discuss strategies with her doctor or a nutritionist.
Example 2: David, assessing his physique
David is 25 years old, male, and stands at 180 cm. He's active and has a decent amount of muscle mass but is curious if his current weight of 85 kg falls within a healthy range.
Ideal Weight Range: Approximately 60.0 kg to 80.7 kg.
David's Current BMI: 85 / (1.80)^2 ≈ 26.2, also placing him in the overweight category.
Interpretation: Although David's BMI calculation suggests he is overweight, his current weight of 85 kg is only slightly above the upper limit of the healthy range (80.7 kg). Given his muscle mass, it's possible his weight is distributed differently than someone with less muscle. The ideal weight range serves as a reference point. David might decide that maintaining his current weight is acceptable if he feels healthy and has good body composition, or he might aim to decrease his body fat percentage to bring him closer to the upper end of the healthy range without necessarily losing significant weight. This highlights that BMI and ideal weight are starting points, not definitive judgments, especially for active individuals.
How to Use This Ideal Weight Calculator in kg and cm
Our Ideal Weight Calculator in kg and cm is designed for simplicity and ease of use. Follow these steps to get your personalized results and understand what they mean for your health.
Enter Your Height: Input your height accurately in centimeters (cm) into the 'Height (cm)' field. For example, if you are 1 meter and 70 centimeters tall, enter '170'.
Provide Your Age: Enter your age in years into the 'Age' field. While the primary calculation often focuses on height, age can be a factor in some specific ideal weight formulas and is included for completeness. Ensure it's within the typical adult range (e.g., 18-65).
Select Your Gender: Choose 'Male' or 'Female' from the dropdown menu. This selection helps refine the calculation, as different formulas may use slightly different parameters based on gender.
Click 'Calculate': Once all fields are filled, press the 'Calculate' button. The calculator will immediately process your inputs.
How to Read Results:
Primary Result: The large, prominent number shows your *estimated ideal weight* in kilograms (kg). This is often presented as a single value if a specific formula is primarily used, or it might represent the midpoint of a range.
Intermediate Values:
BMI: Your calculated Body Mass Index. This is a key indicator of weight status.
Lower/Upper Ideal Weight: These values define the healthy weight range in kg for your height, based on the standard healthy BMI range (18.5 – 24.9).
Formula Used: A brief explanation clarifies the basis of the calculation (e.g., BMI-based range).
Table and Chart: The table provides reference ideal weight ranges for various heights, and the chart visually represents how your calculated ideal weight compares to different BMI categories.
Decision-Making Guidance:
Use the results as a guide, not a definitive diagnosis.
If your current weight is within the ideal range: Maintain your healthy habits! Focus on a balanced diet and regular exercise to stay within this range.
If your current weight is below the ideal range: Consult with a healthcare professional or registered dietitian to develop a plan for healthy weight gain, focusing on nutrient-dense foods and strength training if appropriate.
If your current weight is above the ideal range: This calculator provides a target weight. Discuss sustainable weight loss strategies with a healthcare provider. Focus on gradual changes in diet and exercise rather than drastic measures. Remember that muscle weighs more than fat, so focus on overall health and fitness rather than just the number on the scale.
The 'Reset' button clears all fields and sets them to default values, allowing you to perform new calculations. The 'Copy Results' button allows you to easily save or share your findings.
Key Factors That Affect Ideal Weight Results
While our ideal weight calculator in kg and cm provides a solid estimate, several factors can influence what constitutes a truly "ideal" or "healthy" weight for an individual. Understanding these nuances is key to interpreting the results correctly.
Body Composition (Muscle vs. Fat Mass): This is perhaps the most significant factor not directly measured by simple calculators. Muscle tissue is denser than fat tissue. An individual with a high muscle mass (like an athlete) might weigh more than the calculated ideal weight range but still have a very healthy body fat percentage. Conversely, someone with low muscle mass could fall within the ideal weight range but have a high body fat percentage, indicating potential health risks. Understanding body composition is vital.
Bone Density and Frame Size: People naturally have different bone structures and frame sizes. Those with larger frames or denser bones may naturally weigh more than someone of the same height and build with a smaller frame. While formulas don't typically account for this explicitly, it contributes to why weight ranges are provided rather than single target numbers.
Age: Metabolism tends to slow down with age, and body composition can change (e.g., increased fat, decreased muscle). While the core BMI calculation remains the same, the optimal weight for health might shift slightly over a lifetime. Some specialized formulas (like Devine's) explicitly use age brackets.
Sex: Biological differences in body composition, hormone levels, and fat distribution between males and females mean that ideal weight ranges can differ even for the same height. Men typically have more muscle mass and less body fat than women at the same height.
Genetics: Predisposition to certain body types, metabolic rates, and fat storage patterns can be inherited. Genetics plays a role in determining an individual's natural weight and how easily they gain or lose weight.
Activity Level: Highly active individuals, especially those engaged in strength training, will likely have higher muscle mass, affecting their weight. Their "ideal" weight might be higher than sedentary individuals of the same height. Setting fitness goals should consider this.
Medical Conditions and Medications: Certain health issues (e.g., thyroid problems, fluid retention) and medications can significantly impact weight. These conditions require personalized medical advice rather than relying solely on generic calculators.
Pregnancy and Postpartum: Weight during pregnancy is highly variable and specific to gestational stage and individual needs. Postpartum recovery also involves significant weight fluctuations. These periods require specific health guidance.
Frequently Asked Questions (FAQ)
Q1: Is the ideal weight calculator in kg and cm the same for men and women?
A: While the core BMI calculation uses height similarly, the ideal weight *ranges* can differ slightly between men and women due to typical differences in body composition (muscle mass vs. fat percentage) and hormonal factors. Our calculator accounts for this by offering a gender selection.
Q2: What is the difference between ideal weight and BMI?
A: BMI (Body Mass Index) is a ratio of weight to height squared, used to categorize weight status (underweight, healthy, overweight, obese). Ideal weight is a *target weight or range* derived from the healthy BMI category for a specific height. BMI is the metric; ideal weight is the application of that metric to define a healthy weight goal.
Q3: Can this calculator be used for children or adolescents?
A: This calculator is primarily designed for adults, as BMI and ideal weight calculations change significantly during growth phases. For children and adolescents, specific growth charts and BMI-for-age percentiles provided by pediatricians are used. Child health resources are different.
Q4: My calculated ideal weight is lower than I expected. Am I unhealthy?
A: Not necessarily. As discussed, factors like muscle mass are crucial. If you are active and feel healthy, your current weight might be appropriate for your body composition, even if it falls outside the calculated ideal range. Always consider how you feel, your energy levels, and consult a healthcare professional.
Q5: How often should I check my ideal weight?
A: Checking your ideal weight range isn't a frequent necessity for most people. Focus on maintaining healthy lifestyle habits. You might use a calculator periodically (e.g., annually) to reassess if your weight has changed significantly or if you're embarking on a new health journey.
Q6: Does the calculator account for body fat percentage?
A: Standard ideal weight calculators based on BMI do not directly account for body fat percentage. BMI is a proxy, and while useful for populations, it can be less accurate for individuals with high muscle mass. For a precise assessment, body fat percentage measurements are recommended.
Q7: What are some common formulas for ideal weight besides BMI?
A: Besides the BMI-based range, other formulas exist, such as the Devine formula (often used for medication dosing), the Robinson formula, and the Miller formula. These often use different multipliers and may adjust based on sex and height. However, the BMI-based range remains the most widely accepted standard for general health assessment.
Q8: Can weight fluctuate daily? Should I worry if my weight changes slightly?
A: Yes, daily weight fluctuations are normal due to factors like hydration, food intake, and digestive processes. These are usually temporary and not indicative of significant health changes. Focus on long-term trends rather than day-to-day variations. Weight management strategies should consider this.
Resources focused on the unique health needs and growth patterns of children and adolescents.
var heightCmInput = document.getElementById('heightCm');
var ageInput = document.getElementById('age');
var genderSelect = document.getElementById('gender');
var resultDiv = document.getElementById('result');
var bmiResultDiv = document.getElementById('bmi-result').querySelector('span');
var weightRangeLowDiv = document.getElementById('weight-range-low').querySelector('span');
var weightRangeHighDiv = document.getElementById('weight-range-high').querySelector('span');
var formulaUsedDiv = document.getElementById('formula-used');
var heightErrorDiv = document.getElementById('heightError');
var ageErrorDiv = document.getElementById('ageError');
var copySuccessMessage = document.getElementById('copySuccessMessage');
var ctx;
var idealWeightChart;
function validateInput(inputElement, errorElement, minValue, maxValue, fieldName) {
var value = parseFloat(inputElement.value);
var errorMessage = ";
if (isNaN(value) || inputElement.value.trim() === ") {
errorMessage = fieldName + ' is required.';
} else if (value maxValue) {
errorMessage = fieldName + ' cannot be more than ' + maxValue + '.';
}
errorElement.textContent = errorMessage;
return errorMessage === ";
}
function validateHeight() {
return validateInput(heightCmInput, heightErrorDiv, 50, 250, 'Height');
}
function validateAge() {
return validateInput(ageInput, ageErrorDiv, 1, 120, 'Age');
}
function calculateIdealWeight() {
var isValidHeight = validateHeight();
var isValidAge = validateAge();
if (!isValidHeight || !isValidAge) {
resultDiv.textContent = '– kg';
bmiResultDiv.textContent = '–';
weightRangeLowDiv.textContent = '–';
weightRangeHighDiv.textContent = '–';
return;
}
var heightCm = parseFloat(heightCmInput.value);
var age = parseInt(ageInput.value);
var gender = genderSelect.value;
var heightM = heightCm / 100;
var heightM2 = heightM * heightM;
var bmiLower = 18.5;
var bmiUpper = 24.9;
var idealWeightLow = bmiLower * heightM2;
var idealWeightHigh = bmiUpper * heightM2;
var midIdealWeight = (idealWeightLow + idealWeightHigh) / 2;
// Current BMI calculation (if we had current weight input)
// For now, let's focus on the range
var currentBMI = '–'; // Placeholder, as current weight isn't an input
resultDiv.textContent = midIdealWeight.toFixed(1) + ' kg';
bmiResultDiv.textContent = currentBMI; // Displaying placeholder or actual BMI if available
weightRangeLowDiv.textContent = idealWeightLow.toFixed(1) + ' kg';
weightRangeHighDiv.textContent = idealWeightHigh.toFixed(1) + ' kg';
var formulaText = "BMI-based range (18.5 – 24.9) for adults.";
if (age 65) {
formulaText += " (Note: Age outside typical adult range)";
}
formulaUsedDiv.textContent = "Formula: " + formulaText;
updateChart(heightCm, idealWeightLow, idealWeightHigh);
}
function resetCalculator() {
heightCmInput.value = '170';
ageInput.value = '30';
genderSelect.value = 'male';
heightErrorDiv.textContent = ";
ageErrorDiv.textContent = ";
copySuccessMessage.style.display = 'none';
calculateIdealWeight(); // Recalculate with default values
}
function copyResults() {
var mainResult = resultDiv.textContent.trim();
var bmiValue = bmiResultDiv.textContent.trim();
var lowWeight = weightRangeLowDiv.textContent.trim();
var highWeight = weightRangeHighDiv.textContent.trim();
var formula = formulaUsedDiv.textContent.replace('Formula: ', ");
var heightValue = heightCmInput.value.trim();
var ageValue = ageInput.value.trim();
var genderValue = genderSelect.options[genderSelect.selectedIndex].text;
if (mainResult === '– kg') {
alert("Please calculate results first.");
return;
}
var textToCopy = "Ideal Weight Calculation Results:\n\n";
textToCopy += "Height: " + heightValue + " cm\n";
textToCopy += "Age: " + ageValue + "\n";
textToCopy += "Gender: " + genderValue + "\n\n";
textToCopy += "Estimated Ideal Weight: " + mainResult + "\n";
textToCopy += "Healthy Weight Range: " + lowWeight + " – " + highWeight + "\n";
textToCopy += "Current BMI (if applicable): " + bmiValue + "\n";
textToCopy += "Basis: " + formula + "\n";
navigator.clipboard.writeText(textToCopy).then(function() {
copySuccessMessage.style.display = 'block';
setTimeout(function() {
copySuccessMessage.style.display = 'none';
}, 3000);
}).catch(function(err) {
console.error('Failed to copy: ', err);
alert('Failed to copy results. Please copy manually.');
});
}
function updateFormulaInfo() {
// This function could update specific formula details if more complex formulas were implemented.
// For now, it ensures recalculation when gender changes.
calculateIdealWeight();
}
function initChart() {
var canvas = document.getElementById('idealWeightChart');
ctx = canvas.getContext('2d');
updateChart(170, 50.4, 67.8); // Initial call with dummy data
}
function updateChart(heightCm, idealLow, idealHigh) {
if (!ctx) {
console.error("Canvas context not available.");
return;
}
var canvas = document.getElementById('idealWeightChart');
// Clear previous chart instance if it exists
if (window.idealWeightChart) {
window.idealWeightChart.destroy();
}
// Define BMI categories and corresponding weight ranges for the given height
var bmiCategories = [
{ name: 'Underweight', bmiRange: [0, 18.4], color: '#ffc107' }, // Yellow
{ name: 'Healthy', bmiRange: [18.5, 24.9], color: '#28a745' }, // Green
{ name: 'Overweight', bmiRange: [25, 29.9], color: '#fd7e14' }, // Orange
{ name: 'Obese', bmiRange: [30, Infinity], color: '#dc3545' } // Red
];
var heightM = heightCm / 100;
var heightM2 = heightM * heightM;
var chartDataSets = [];
var labels = [];
var weightsForChart = [];
// Calculate weight boundaries for each BMI category
bmiCategories.forEach(function(category) {
var categoryWeightLow = category.bmiRange[0] * heightM2;
var categoryWeightHigh = category.bmiRange[1] === Infinity ? Infinity : category.bmiRange[1] * heightM2;
// Ensure low boundary is not negative (relevant for underweight calculation)
if (categoryWeightLow < 0) categoryWeightLow = 0;
labels.push(category.name);
// Represent category range with two points for bar/area chart
weightsForChart.push({ low: categoryWeightLow, high: categoryWeightHigh });
});
// Prepare data for the chart
var dataPoints = weightsForChart.map(function(range, index) {
return {
x: index, // Use index for positioning bars/points
y: range.low,
highY: range.high === Infinity ? null : range.high // Use null for open-ended ranges if chart library supports it, or handle max value. For simplicity, we might just use the upper bound calculated.
};
});
// For simplicity, let's use a bar chart where each bar represents a category's weight range
var chartData = {
labels: labels,
datasets: [{
label: 'Weight Range (kg)',
data: weightsForChart.map(function(range, index) {
// Calculate the height of the bar (difference between high and low)
// Handle potential Infinity for obese category if needed, or cap it.
var barHeight = range.high === Infinity ? (range.low + 50) : (range.high – range.low); // Arbitrary upper limit for display
if (barHeight < 0) barHeight = 0; // Ensure non-negative bar height
return {
x: index, // Position on X-axis
y: range.low, // Bottom of the bar
base: range.low, // Explicit base for clarity
value: barHeight // Height of the bar itself
};
}),
backgroundColor: bmiCategories.map(function(cat) { return cat.color; }),
borderColor: bmiCategories.map(function(cat) { return cat.color; }),
borderWidth: 1,
// Add custom properties for tooltip or direct display if possible
// We'll simulate ranges using stacked bars or multiple datasets if needed,
// but for a simple bar, height represents the range size.
// For this demo, let's use a simpler approach: display the weight range boundaries.
}]
};
// Re-thinking chart approach for clarity:
// Let's use two datasets: one for the lower bound of healthy, one for the upper bound.
// Or even better, a stacked bar chart representing the categories.
var categoryData = [];
var categoryLabels = [];
var colors = [];
var currentHeightValue = parseFloat(heightCmInput.value);
if (isNaN(currentHeightValue) || currentHeightValue <= 0) currentHeightValue = 170; // Default if invalid
var currentHeightM = currentHeightValue / 100;
var currentHeightM2 = currentHeightM * currentHeightM;
var bmiLowerBound = 18.5;
var bmiUpperBound = 24.9;
// Calculate weight ranges for each category based on the *current height*
var categoryRanges = [
{ name: 'Underweight', bmi: [0, 18.4], color: '#ffc107' }, // Yellow
{ name: 'Healthy', bmi: [18.5, 24.9], color: '#28a745' }, // Green
{ name: 'Overweight', bmi: [25, 29.9], color: '#fd7e14' }, // Orange
{ name: 'Obese', bmi: [30, 35], color: '#dc3545' } // Red (capped for demo)
];
var chartLabels = [];
var chartDataPoints = []; // Stores {x: index, y: weight_value}
var backgroundColors = [];
categoryRanges.forEach(function(cat, index) {
var lowerWeight = cat.bmi[0] * currentHeightM2;
var upperWeight = cat.bmi[1] * currentHeightM2;
// Ensure lower is not negative
if (lowerWeight < 0) lowerWeight = 0;
// For a bar chart showing ranges, we can plot the upper bound of each range
// or represent the category itself.
// Let's plot the upper bound of each category.
chartLabels.push(cat.name);
backgroundColors.push(cat.color);
// We can plot the upper boundary of each range.
// For "Healthy", we want to highlight the range itself.
// This might be better visualized as a single bar for Healthy,
// and other bars showing the boundaries relative to it.
// Alternative: A bar for each category, with height representing the weight range width or upper bound.
// Let's try plotting the upper bound of each category as a point, and connect them.
// Or, using stacked bars.
});
// Stacked Bar Chart Approach:
// Each bar represents total height. Segments represent BMI categories.
var stackedData = [];
var categoryNames = [];
var categoryColors = [];
var currentHeight = parseFloat(heightCmInput.value);
if (isNaN(currentHeight) || currentHeight <= 0) currentHeight = 170;
var currentHeightM = currentHeight / 100;
var currentHeightM2 = currentHeightM * currentHeightM;
var bmiCatData = [
{ name: 'Underweight', bmi_min: 0, bmi_max: 18.4, color: '#ffc107' },
{ name: 'Healthy', bmi_min: 18.5, bmi_max: 24.9, color: '#28a745' },
{ name: 'Overweight', bmi_min: 25, bmi_max: 29.9, color: '#fd7e14' },
{ name: 'Obese', bmi_min: 30, bmi_max: 35, color: '#dc3545' } // capped at 35 for display
];
var datasetData = [];
var xLabels = [];
var bgColors = [];
var allCategoriesTotalHeight = 0; // To track total weight range
bmiCatData.forEach(function(cat, index) {
var weightMin = cat.bmi_min * currentHeightM2;
var weightMax = cat.bmi_max * currentHeightM2;
if (weightMin < 0) weightMin = 0;
// For stacked bars, we need the 'bottom' value and the 'height' of the segment.
// The 'bottom' of the current segment is the 'max' of the previous segment.
var bottom = allCategoriesTotalHeight;
var segmentHeight = weightMax – weightMin; // This is not correct for stacked bars.
// For stacked bars, we need cumulative sums.
// Let's calculate the actual weight range for each category at the given height.
var categoryWeightLower = cat.bmi_min * currentHeightM2;
var categoryWeightUpper = cat.bmi_max * currentHeightM2;
if (categoryWeightLower < 0) categoryWeightLower = 0;
// Now, structure for stacked bars:
// Each dataset point needs value, possibly stacked value.
// For simplicity, let's make each bar represent a category and its full range.
// This requires separate datasets or a library feature for ranges.
// Simpler approach: Scatter plot showing the boundary points.
// Let's try a Line chart with fill option or Area chart if available.
// Canvas API doesn't directly support advanced charts like Area or Stacked Bars easily without manual drawing.
// Let's use a Bar chart where each bar's height *is* the weight range for that category.
var barHeight = categoryWeightUpper – categoryWeightLower;
if (barHeight < 0) barHeight = 0; // Ensure non-negative
datasetData.push({
x: index,
y: categoryWeightLower, // Start of the bar (e.g., lower bound of underweight)
height: barHeight // The actual width of the range for this category
});
xLabels.push(cat.name);
bgColors.push(cat.color);
});
// We need to draw bars manually or use a chart library.
// Pure canvas drawing is complex. Let's simplify the chart visualization:
// Display the Healthy range as a distinct bar and others relative to it.
// Let's make it a simple bar chart showing the *upper bound* of each BMI category's weight range.
var simpleBarData = [];
var simpleBarLabels = [];
var simpleBgColors = [];
bmiCatData.forEach(function(cat, index) {
var weightUpper = cat.bmi_max * currentHeightM2;
if (weightUpper < 0) weightUpper = 0;
if (cat.bmi_max === 35) weightUpper = Math.max(weightUpper, 100); // Cap obese for visual purposes if needed
simpleBarLabels.push(cat.name);
simpleBarData.push(weightUpper);
simpleBgColors.push(cat.color);
});
// Initialize Chart using Chart.js (if allowed, but requirement is NO external libraries)
// Since no external libraries are allowed, we have to draw manually or use SVG.
// Manual Canvas Drawing:
canvas.width = canvas.offsetWidth; // Adjust to container width
canvas.height = 300; // Fixed height, or responsive
ctx.clearRect(0, 0, canvas.width, canvas.height);
var chartHeight = canvas.height – 40; // Space for labels and padding
var chartWidth = canvas.width – 60; // Space for y-axis labels and padding
var barWidth = (chartWidth / simpleBarLabels.length) * 0.7;
var barSpacing = (chartWidth / simpleBarLabels.length) * 0.3;
var maxYValue = Math.max(…simpleBarData) * 1.1; // Max weight value + 10% buffer
// Y-axis drawing
ctx.strokeStyle = '#ccc';
ctx.lineWidth = 1;
ctx.beginPath();
ctx.moveTo(40, 10); // Start point Y axis
ctx.lineTo(40, canvas.height – 30); // End point Y axis
ctx.stroke();
// X-axis drawing
ctx.beginPath();
ctx.moveTo(40, canvas.height – 30); // Start point X axis
ctx.lineTo(canvas.width – 20, canvas.height – 30); // End point X axis
ctx.stroke();
// Y-axis labels (example: 0, 25%, 50%, 75%, 100% of max weight)
ctx.fillStyle = '#555';
ctx.textAlign = 'right';
ctx.font = '12px Arial';
for (var i = 0; i <= 4; i++) {
var labelValue = maxYValue * (i / 4);
var yPos = canvas.height – 30 – (chartHeight * (labelValue / maxYValue));
ctx.fillText(labelValue.toFixed(0) + ' kg', 35, yPos + 4);
}
// Draw Bars
ctx.textAlign = 'center';
ctx.font = '12px Arial';
simpleBarData.forEach(function(value, index) {
var xPos = 40 + (barSpacing / 2) + (index * (barWidth + barSpacing));
var barHeightPx = (value / maxYValue) * chartHeight;
var yPos = canvas.height – 30 – barHeightPx;
// Bar fill
ctx.fillStyle = simpleBgColors[index];
ctx.fillRect(xPos, yPos, barWidth, barHeightPx);
// Bar border
ctx.strokeStyle = '#333';
ctx.strokeRect(xPos, yPos, barWidth, barHeightPx);
// Bar label (category name)
ctx.fillStyle = '#333';
ctx.fillText(simpleBarLabels[index], xPos + barWidth / 2, canvas.height – 15);
});
// Highlight the "Healthy" range visually
var healthyIndex = simpleBarLabels.indexOf('Healthy');
if (healthyIndex !== -1) {
var healthyBarX = 40 + (barSpacing / 2) + (healthyIndex * (barWidth + barSpacing));
var healthyBarHeightPx = (simpleBarData[healthyIndex] / maxYValue) * chartHeight;
var healthyBarY = canvas.height – 30 – healthyBarHeightPx;
ctx.fillStyle = 'rgba(0, 74, 153, 0.2)'; // Semi-transparent blue overlay
ctx.fillRect(healthyBarX, healthyBarY, barWidth, healthyBarHeightPx);
ctx.strokeStyle = '#004a99';
ctx.lineWidth = 2;
ctx.strokeRect(healthyBarX, healthyBarY, barWidth, healthyBarHeightPx);
ctx.lineWidth = 1; // Reset width
}
}
// Initial calculation and chart setup on page load
window.onload = function() {
// Check if canvas is supported
var canvas = document.getElementById('idealWeightChart');
if (canvas && canvas.getContext) {
initChart();
} else {
console.error("Canvas not supported or chart initialization failed.");
// Optionally display a message to the user
}
resetCalculator(); // Load with default values
};