Enter your lean body mass in kilograms (muscle, bone, organs, etc.).
Your Body Fat Percentage
Key Metrics
Formula Used: BF% = (Body Fat Mass / Total Body Weight) * 100
Body Fat Mass vs. Lean Body Mass Composition
Metric
Value
Unit
Total Body Weight
kg
Body Fat Mass
kg
Lean Body Mass
kg
Body Fat Percentage
%
Body Composition Breakdown
Understanding Your BF Percentage
The BF percentage calculator is an indispensable tool for anyone serious about their health, fitness, and body composition.
It provides a numerical value representing the proportion of your body weight that is composed of fat tissue. This metric is crucial for assessing overall health, monitoring progress towards fitness goals, and identifying potential health risks associated with excess body fat.
Understanding your body fat percentage goes beyond simple weight tracking, offering deeper insights into your physical condition.
What is BF Percentage?
Your BF percentage (Body Fat Percentage) is the total mass of fat in your body divided by your total body mass, expressed as a percentage. It's a more accurate indicator of health and fitness than traditional weight measurements alone. While a certain amount of body fat is essential for bodily functions (hormone regulation, insulation, nutrient absorption), excessive body fat can increase the risk of numerous health problems, including cardiovascular disease, type 2 diabetes, and certain cancers. Conversely, extremely low body fat can also pose health risks. The BF percentage calculator helps you quantify this vital metric.
Who should use it:
Individuals aiming to lose fat or gain muscle.
Athletes and fitness enthusiasts monitoring body composition.
Anyone seeking a more comprehensive understanding of their health beyond just weight.
People managing weight-related health conditions.
Common misconceptions:
"Weight equals fat": You can be at a healthy weight but have a high body fat percentage (skinny fat), or be overweight but have a low body fat percentage due to high muscle mass.
"All fat is bad": Essential body fat is necessary for survival and hormone function.
"One-size-fits-all healthy range": Ideal body fat percentages vary significantly based on age, sex, and activity level.
BF Percentage Formula and Mathematical Explanation
Calculating your body fat percentage is straightforward once you have the necessary measurements. The fundamental formula relies on understanding the components of your total body mass.
Body Fat Percentage (%) = (Body Fat Mass / Total Body Weight) * 100
Let's break down the variables:
Variable Name
Meaning
Unit
Typical Range
Body Fat Mass (BFM)
The total mass of fat in your body.
Kilograms (kg)
Highly variable (e.g., 5 kg – 50+ kg)
Total Body Weight (TBW)
Your complete body mass, including fat, muscle, bone, water, etc.
Kilograms (kg)
Highly variable (e.g., 40 kg – 150+ kg)
Body Fat Percentage (BF%)
The proportion of your total body weight that is fat.
Percentage (%)
Generally 10% – 40% (varies by sex, age, fitness)
Lean Body Mass (LBM)
The mass of your body excluding fat (muscle, bone, organs, water).
Kilograms (kg)
Highly variable (e.g., 30 kg – 120+ kg)
This calculator also uses derived values like Fat-to-Lean Ratio and Weight-to-Fat Ratio, which can offer additional insights into body composition. For example, Lean Body Mass can be calculated as:
Lean Body Mass (LBM) = Total Body Weight – Body Fat Mass
And conversely, if you know your LBM and Total Body Weight, you can find Body Fat Mass:
Body Fat Mass = Total Body Weight – Lean Body Mass
Sarah is a 30-year-old woman who trains regularly and wants to track her progress. She weighs 65 kg and has measured her body fat mass to be 13 kg.
Inputs:
Total Body Weight: 65 kg
Body Fat Mass: 13 kg
Using the formula: BF% = (13 kg / 65 kg) * 100 = 20%
Intermediate Calculations:
Lean Body Mass: 65 kg – 13 kg = 52 kg
Weight-to-Fat Ratio: 65 kg / 13 kg = 5:1
Fat-to-Lean Ratio: 13 kg / 52 kg = 0.25 (or 1:4)
Interpretation: Sarah has a body fat percentage of 20%. This is generally considered a healthy and fit range for women. She can use this as a baseline and monitor changes as she adjusts her training and nutrition.
Example 2: Someone Focusing on Fat Loss
John is a 45-year-old man aiming to reduce his body fat. He currently weighs 90 kg, and his body fat mass is estimated at 27 kg. He wants to reach 20% body fat.
Inputs:
Total Body Weight: 90 kg
Body Fat Mass: 27 kg
Using the formula: BF% = (27 kg / 90 kg) * 100 = 30%
Intermediate Calculations:
Lean Body Mass: 90 kg – 27 kg = 63 kg
Weight-to-Fat Ratio: 90 kg / 27 kg ≈ 3.33:1
Fat-to-Lean Ratio: 27 kg / 63 kg ≈ 0.43 (or 1:2.33)
Interpretation: John's current body fat percentage is 30%, which is in the obese range for men. His goal is 20%. He knows he needs to reduce his body fat mass while ideally maintaining or increasing his lean body mass. The BF percentage calculator helps him set a clear target and track progress. To reach 20% BF with his current LBM of 63 kg, his target weight would be approximately 78.75 kg (63 kg / 0.80). This means he needs to lose about 11.25 kg of fat.
How to Use This BF Percentage Calculator
Using our BF percentage calculator is simple and provides immediate results. Follow these steps:
Measure Accurately: Obtain your Total Body Weight (in kg), Body Fat Mass (in kg), and/or Lean Body Mass (in kg). These can be measured using scales with body composition analysis, calipers, bioelectrical impedance devices, or DEXA scans (for the most accuracy). Ensure you use consistent measurement methods over time.
Input Values: Enter your measured values into the corresponding fields: "Body Weight (kg)", "Body Fat Mass (kg)", and "Lean Body Mass (kg)". You only need to input two of these values (e.g., Weight and Fat Mass, or Weight and Lean Mass), as the third can be derived.
Calculate: Click the "Calculate" button.
Review Results: The calculator will display your calculated Body Fat Percentage (BF%) as the primary result. It will also show key intermediate values like the Weight-to-Fat Ratio and Fat-to-Lean Ratio, alongside a detailed breakdown in the table.
Interpret: Compare your BF% to standard ranges for your age and sex to understand your health status. Use the intermediate metrics for a more nuanced view of your body composition.
Track Progress: Use the "Copy Results" button to save your findings or compare them with previous measurements. Regularly using the calculator helps you monitor the effectiveness of your diet and exercise programs.
Reset: Click "Reset" to clear all fields and start a new calculation.
Key Factors That Affect BF Percentage Results
Several factors influence your body fat percentage and how it's measured. Understanding these can help you interpret your results more accurately and make informed decisions about your health journey.
Genetics: Your genetic makeup plays a significant role in where your body stores fat and your predisposition to gain or lose it. While genetics aren't destiny, they provide a baseline.
Age: Metabolism tends to slow down with age, and body composition often shifts, with a tendency to gain fat and lose muscle mass if lifestyle habits aren't adjusted. This can increase BF% even if weight remains stable.
Sex: Biological sex influences hormone levels and body composition. Women naturally carry a higher percentage of essential body fat than men due to reproductive functions.
Diet and Nutrition: Caloric intake versus expenditure is paramount. Consuming more calories than you burn leads to fat gain, increasing BF%. The quality of food (macronutrient balance) also impacts muscle retention and fat loss efforts. Proper nutrition is key to optimizing results from any nutrition calculator.
Physical Activity Level: Regular exercise, particularly a combination of cardiovascular and strength training, is crucial for both burning calories and building lean muscle mass. Muscle tissue is metabolically active and helps in fat management.
Hormonal Balance: Hormones like cortisol, insulin, testosterone, and estrogen can significantly impact body fat storage and distribution. Imbalances can lead to increased abdominal fat or difficulty losing fat.
Hydration Levels: While water doesn't have mass that directly impacts fat calculation, dehydration can affect the accuracy of some measurement devices (like bioelectrical impedance) by altering electrical conductivity.
Measurement Method Accuracy: Different methods (calipers, BIA scales, DEXA) have varying degrees of accuracy and precision. Using the same method consistently is more important than chasing absolute precision if using less accurate tools.
Frequently Asked Questions (FAQ)
What is considered a "healthy" body fat percentage?
Healthy ranges vary by age and sex. Generally, for men, 15-20% is considered fit, while 20-25% is average. For women, 20-25% is fit, and 25-30% is average. Athletes often have lower ranges. However, these are guidelines, and individual health should be assessed holistically. Our BF percentage calculator provides the number; consult a healthcare professional for interpretation.
Can I use weight in pounds (lbs) for this calculator?
No, this specific calculator requires all inputs to be in kilograms (kg). You'll need to convert your measurements if they are in pounds. (1 kg ≈ 2.20462 lbs).
What is the difference between Body Fat Mass and Lean Body Mass?
Body Fat Mass is the weight of all the fat in your body. Lean Body Mass (LBM) is everything else: muscle, bone, organs, skin, and water. LBM is crucial for metabolism and overall physical function.
Is it possible to have too little body fat?
Yes. While reducing excess fat is healthy, extremely low body fat levels (typically below 10% for men and 15% for women) can be dangerous. Essential body fat is required for hormone production, organ protection, and nutrient absorption. Very low levels can lead to hormonal disruptions, fatigue, and weakened immunity.
How often should I measure my body fat percentage?
For individuals actively managing their body composition, measuring every 2-4 weeks is often recommended. This frequency allows you to track meaningful changes without being discouraged by daily fluctuations. Always use the same measurement method for consistency.
Why is my body fat percentage high even if I exercise regularly?
Several reasons:
Diet: You might be consuming more calories than you burn, even with exercise.
Muscle Mass: If you have a lot of muscle, it can increase your weight and potentially skew percentage calculations if fat mass isn't measured accurately.
Type of Exercise: A lack of sufficient resistance training might hinder muscle gain, which is key for improving body composition.
Measurement Error: The method used might be inaccurate.
Can this calculator predict health risks?
While body fat percentage is a health indicator, this calculator itself does not diagnose health risks. High body fat percentages are *associated* with increased risks. For a health assessment, consult a medical professional.
What does the Weight-to-Fat Ratio tell me?
The Weight-to-Fat Ratio compares your total body weight to your body fat mass. A lower ratio (closer to 1:1) indicates a higher percentage of body fat, while a higher ratio (e.g., 5:1 or more) suggests a lower body fat percentage, often associated with greater lean mass.
Related Tools and Internal Resources
BMI Calculator – A simpler measure of weight status relative to height, though it doesn't distinguish between fat and muscle.
BMR Calculator – Estimates your Basal Metabolic Rate, the calories your body burns at rest, a key component of energy expenditure.
TDEE Calculator – Calculates your Total Daily Energy Expenditure, helping you understand your overall calorie needs for weight management.
Weight Loss Guide – Provides practical strategies and tips for sustainable weight and fat loss.
Muscle Building Guide – Offers advice on how to effectively gain muscle mass, which can improve body composition.
Calorie Calculator – Helps determine daily calorie intake targets based on your goals and activity level.
var canvas = document.getElementById("bfChart");
var ctx = canvas.getContext("2d");
var bfChartInstance = null;
function drawChart(bodyFatKg, leanBodyMassKg) {
if (bfChartInstance) {
bfChartInstance.destroy();
}
var totalWeight = parseFloat(document.getElementById("bodyWeight").value);
if (isNaN(totalWeight) || totalWeight 0 ? bodyFatKg : 0;
var leanValue = leanBodyMassKg > 0 ? leanBodyMassKg : 0;
if (totalWeight 100) {
var excess = (fatPercentage + leanPercentage) – 100;
if(fatPercentage > leanPercentage) {
fatPercentage -= excess;
} else {
leanPercentage -= excess;
}
// Ensure they don't go below zero
fatPercentage = Math.max(0, fatPercentage);
leanPercentage = Math.max(0, leanPercentage);
}
bfChartInstance = new Chart(ctx, {
type: 'doughnut', // Or 'pie'
data: {
labels: ['Body Fat', 'Lean Body Mass'],
datasets: [{
data: [fatPercentage, leanPercentage],
backgroundColor: [
'rgba(220, 53, 69, 0.7)', // Red for Fat
'rgba(40, 167, 69, 0.7)' // Green for Lean
],
borderColor: [
'rgba(220, 53, 69, 1)',
'rgba(40, 167, 69, 1)'
],
borderWidth: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
legend: {
position: 'bottom',
},
tooltips: {
callbacks: {
label: function(tooltipItem, data) {
var dataset = data.datasets[0];
var currentValue = dataset.data[tooltipItem.index];
return currentValue.toFixed(1) + '%';
}
}
}
}
});
}
// Simple Chart.js like structure for the canvas
// This is a placeholder. A real implementation would require a charting library or manual SVG/Canvas drawing.
// For this requirement, we'll assume a simplified pure JS drawing approach or dummy it.
// NOTE: Real Chart.js is not used per requirements. This is a conceptual placeholder.
// To fulfill the "pure SVG or native canvas" strictly, manual drawing logic would be needed here.
// Given the complexity, we'll simulate the update and assume a canvas drawing context exists.
// A full native canvas drawing implementation is extensive. Let's add a basic placeholder drawing.
function drawBasicCanvasChart(bodyFatKg, leanBodyMassKg) {
// Clear previous drawing if any
ctx.clearRect(0, 0, canvas.width, canvas.height);
var totalWeight = parseFloat(document.getElementById("bodyWeight").value);
if (isNaN(totalWeight) || totalWeight <= 0) {
totalWeight = bodyFatKg + leanBodyMassKg; // Use sum if main weight is invalid
}
if (totalWeight 0 ? bodyFatKg : 0;
var leanValue = leanBodyMassKg > 0 ? leanBodyMassKg : 0;
var fatPercent = (fatValue / totalWeight) * 100;
var leanPercent = (leanValue / totalWeight) * 100;
// Clamp percentages
fatPercent = Math.min(fatPercent, 100);
leanPercent = Math.min(leanPercent, 100);
if (fatPercent + leanPercent > 100) {
var excess = (fatPercent + leanPercent) – 100;
if(fatPercent > leanPercent) fatPercent -= excess; else leanPercent -= excess;
fatPercent = Math.max(0, fatPercent); leanPercent = Math.max(0, leanPercent);
}
var centerX = canvas.width / 2;
var centerY = canvas.height / 2;
var radius = Math.min(centerX, centerY) * 0.8;
var startAngleFat = 0;
var startAngleLean = (fatPercent / 100) * 2 * Math.PI;
// Draw Fat Arc
ctx.fillStyle = 'rgba(220, 53, 69, 0.7)';
ctx.beginPath();
ctx.moveTo(centerX, centerY);
ctx.arc(centerX, centerY, radius, startAngleFat, startAngleFat + (fatPercent / 100) * 2 * Math.PI);
ctx.closePath();
ctx.fill();
// Draw Lean Arc
ctx.fillStyle = 'rgba(40, 167, 69, 0.7)';
ctx.beginPath();
ctx.moveTo(centerX, centerY);
ctx.arc(centerX, centerY, radius, startAngleLean, startAngleLean + (leanPercent / 100) * 2 * Math.PI);
ctx.closePath();
ctx.fill();
// Draw Center Circle (optional, for doughnut effect)
ctx.fillStyle = 'white';
ctx.beginPath();
ctx.arc(centerX, centerY, radius * 0.6, 0, 2 * Math.PI);
ctx.closePath();
ctx.fill();
// Add Labels – basic text positioning
ctx.fillStyle = 'black';
ctx.font = '14px Arial';
ctx.textAlign = 'center';
ctx.fillText('Fat ' + fatPercent.toFixed(1) + '%', centerX + radius * 0.5, centerY – radius * 0.5);
ctx.fillText('Lean ' + leanPercent.toFixed(1) + '%', centerX – radius * 0.5, centerY + radius * 0.5);
}
function validateInput(id, min, max, name) {
var input = document.getElementById(id);
var value = parseFloat(input.value);
var errorDiv = document.getElementById(id + "Error");
var errorPresent = false;
errorDiv.style.display = 'none';
input.style.borderColor = 'var(–border-color)';
if (input.value.trim() === "") {
errorDiv.textContent = name + " is required.";
errorDiv.style.display = 'block';
input.style.borderColor = '#dc3545';
errorPresent = true;
} else if (isNaN(value)) {
errorDiv.textContent = name + " must be a valid number.";
errorDiv.style.display = 'block';
input.style.borderColor = '#dc3545';
errorPresent = true;
} else if (value max) {
errorDiv.textContent = name + " cannot be more than " + max + ".";
errorDiv.style.display = 'block';
input.style.borderColor = '#dc3545';
errorPresent = true;
}
return !errorPresent;
}
function calculateBfPercentage() {
var bodyWeightInput = document.getElementById("bodyWeight");
var bodyFatKgInput = document.getElementById("bodyFatKg");
var leanBodyMassKgInput = document.getElementById("leanBodyMassKg");
var bodyWeight = parseFloat(bodyWeightInput.value);
var bodyFatKg = parseFloat(bodyFatKgInput.value);
var leanBodyMassKg = parseFloat(leanBodyMassKgInput.value);
var isValid = true;
// Clear previous errors
document.getElementById("bodyWeightError").style.display = 'none';
document.getElementById("bodyFatKgError").style.display = 'none';
document.getElementById("leanBodyMassKgError").style.display = 'none';
bodyWeightInput.style.borderColor = 'var(–border-color)';
bodyFatKgInput.style.borderColor = 'var(–border-color)';
leanBodyMassKgInput.style.borderColor = 'var(–border-color)';
// Validation
if (isNaN(bodyWeight) || bodyWeight <= 0) {
document.getElementById("bodyWeightError").textContent = "Body Weight must be a positive number.";
document.getElementById("bodyWeightError").style.display = 'block';
bodyWeightInput.style.borderColor = '#dc3545';
isValid = false;
}
if (isNaN(bodyFatKg) || bodyFatKg < 0) { // Allow 0 fat
document.getElementById("bodyFatKgError").textContent = "Body Fat Mass cannot be negative.";
document.getElementById("bodyFatKgError").style.display = 'block';
bodyFatKgInput.style.borderColor = '#dc3545';
isValid = false;
}
if (isNaN(leanBodyMassKg) || leanBodyMassKg < 0) { // Allow 0 lean mass
document.getElementById("leanBodyMassKgError").textContent = "Lean Body Mass cannot be negative.";
document.getElementById("leanBodyMassKgError").style.display = 'block';
leanBodyMassKgInput.style.borderColor = '#dc3545';
isValid = false;
}
// Check consistency if multiple fields are filled
var filledCount = 0;
if (bodyWeightInput.value.trim() !== "") filledCount++;
if (bodyFatKgInput.value.trim() !== "") filledCount++;
if (leanBodyMassKgInput.value.trim() !== "") filledCount++;
if (filledCount 0 && !isNaN(bodyFatKg) && !isNaN(leanBodyMassKg)) {
if (Math.abs((bodyFatKg + leanBodyMassKg) – bodyWeight) > 0.1) { // Allow small tolerance
// If provided values don't sum up, prioritize the most comprehensive inputs or flag inconsistency.
// Let's recalculate based on two primary inputs if they exist and are valid.
// E.g., if weight and fat are given, calculate lean mass.
if (bodyWeight > 0 && bodyFatKg >= 0 && leanBodyMassKgInput.value.trim() === "") {
leanBodyMassKg = bodyWeight – bodyFatKg;
leanBodyMassKgInput.value = leanBodyMassKg.toFixed(2);
if (leanBodyMassKg 0 && leanBodyMassKg >= 0 && bodyFatKgInput.value.trim() === "") {
bodyFatKg = bodyWeight – leanBodyMassKg;
bodyFatKgInput.value = bodyFatKg.toFixed(2);
if (bodyFatKg = 0 && leanBodyMassKg >= 0 && bodyWeightInput.value.trim() === "") {
bodyWeight = bodyFatKg + leanBodyMassKg;
bodyWeightInput.value = bodyWeight.toFixed(2);
} else if (Math.abs((bodyFatKg + leanBodyMassKg) – bodyWeight) > 0.1) {
// If all three are provided and inconsistent, flag it.
// For simplicity, we'll proceed with the primary calculation using the provided Body Weight and Body Fat Mass if they are valid.
// Or perhaps prioritize the calculation: BF% = (Body Fat Mass / Total Body Weight) * 100
// Let's re-validate the primary inputs needed for the main formula.
if (!validateInput("bodyWeight", 0.1, 1000, "Body Weight") || !validateInput("bodyFatKg", 0, 1000, "Body Fat Mass")) {
isValid = false;
}
}
}
}
}
// Re-check specific value constraints after potential recalculations
if (!validateInput("bodyWeight", 0.1, 1000, "Body Weight")) isValid = false; // Max weight assumption
if (!validateInput("bodyFatKg", 0, 1000, "Body Fat Mass")) isValid = false; // Max fat assumption
if (!validateInput("leanBodyMassKg", 0, 1000, "Lean Body Mass")) isValid = false; // Max lean assumption
// Ensure fat mass is not greater than total weight
if (parseFloat(bodyWeightInput.value) < parseFloat(bodyFatKgInput.value)) {
document.getElementById("bodyFatKgError").textContent = "Body Fat Mass cannot be greater than Total Body Weight.";
document.getElementById("bodyFatKgError").style.display = 'block';
bodyFatKgInput.style.borderColor = '#dc3545';
isValid = false;
}
// Ensure lean mass is not greater than total weight
if (parseFloat(bodyWeightInput.value) = 0;
var useLeanBodyMassKg = !isNaN(leanBodyMassKg) && leanBodyMassKg >= 0;
var useBodyWeight = !isNaN(bodyWeight) && bodyWeight > 0;
if (useBodyWeight && useBodyFatKg) {
bfPercentage = (bodyFatKg / bodyWeight) * 100;
calculatedLeanMass = bodyWeight – bodyFatKg;
calculatedFatMass = bodyFatKg;
calculatedWeight = bodyWeight;
// Update Lean Mass input if it was empty or inconsistent
if (!useLeanBodyMassKg || Math.abs(leanBodyMassKg – calculatedLeanMass) > 0.1) {
leanBodyMassKgInput.value = calculatedLeanMass.toFixed(2);
}
leanBodyMassKg = calculatedLeanMass; // Use the calculated value
} else if (useBodyWeight && useLeanBodyMassKg) {
calculatedFatMass = bodyWeight – leanBodyMassKg;
if (calculatedFatMass < 0) calculatedFatMass = 0; // Cannot be negative
bodyFatKgInput.value = calculatedFatMass.toFixed(2); // Update input
bfPercentage = (calculatedFatMass / bodyWeight) * 100;
calculatedWeight = bodyWeight;
bodyFatKg = calculatedFatMass; // Use the calculated value
} else if (useBodyFatKg && useLeanBodyMassKg) {
calculatedWeight = bodyFatKg + leanBodyMassKg;
bodyWeightInput.value = calculatedWeight.toFixed(2); // Update input
bfPercentage = (bodyFatKg / calculatedWeight) * 100;
calculatedFatMass = bodyFatKg;
} else {
// Insufficient valid data
document.getElementById("result").style.display = 'none';
document.getElementById("intermediateResults").style.display = 'none';
document.getElementById("copyBtn").style.display = 'none';
return;
}
// Final checks on calculated values
bfPercentage = Math.max(0, bfPercentage); // Ensure not negative
calculatedLeanMass = Math.max(0, calculatedLeanMass);
calculatedFatMass = Math.max(0, calculatedFatMass);
calculatedWeight = Math.max(0, calculatedWeight);
// Intermediate Metrics
var weightToFatRatio = calculatedWeight / calculatedFatMass;
var fatToLeanRatio = calculatedFatMass / calculatedLeanMass;
var leanToFatRatio = calculatedLeanMass / calculatedFatMass;
// Display Results
document.getElementById("mainResult").textContent = bfPercentage.toFixed(1) + "%";
document.getElementById("formulaUsed").textContent = "Calculated using: (Body Fat Mass / Total Body Weight) * 100";
document.getElementById("weightToFatRatio").innerHTML = "Weight-to-Fat Ratio: " + (isFinite(weightToFatRatio) ? weightToFatRatio.toFixed(2) + ":1" : "N/A");
document.getElementById("fatToLeanRatio").innerHTML = "Fat-to-Lean Ratio: " + (isFinite(fatToLeanRatio) ? fatToLeanRatio.toFixed(2) + ":1" : "N/A");
document.getElementById("leanToFatRatio").innerHTML = "Lean-to-Fat Ratio: " + (isFinite(leanToFatRatio) ? leanToFatRatio.toFixed(2) + ":1" : "N/A");
// Update Table
document.getElementById("tableWeight").textContent = calculatedWeight.toFixed(2);
document.getElementById("tableFatMass").textContent = calculatedFatMass.toFixed(2);
document.getElementById("tableLeanMass").textContent = calculatedLeanMass.toFixed(2);
document.getElementById("tableBfPerc").textContent = bfPercentage.toFixed(1);
document.getElementById("result").style.display = 'block';
document.getElementById("intermediateResults").style.display = 'block';
document.getElementById("copyBtn").style.display = 'block';
// Update Chart
drawBasicCanvasChart(calculatedFatMass, calculatedLeanMass);
}
function resetCalculator() {
document.getElementById("bodyWeight").value = "";
document.getElementById("bodyFatKg").value = "";
document.getElementById("leanBodyMassKg").value = "";
document.getElementById("result").style.display = 'none';
document.getElementById("intermediateResults").style.display = 'none';
document.getElementById("copyBtn").style.display = 'none';
document.getElementById("bodyWeightError").style.display = 'none';
document.getElementById("bodyFatKgError").style.display = 'none';
document.getElementById("leanBodyMassKgError").style.display = 'none';
document.getElementById("tableWeight").textContent = "";
document.getElementById("tableFatMass").textContent = "";
document.getElementById("tableLeanMass").textContent = "";
document.getElementById("tableBfPerc").textContent = "";
// Clear canvas
if (bfChartInstance) {
bfChartInstance.destroy();
bfChartInstance = null;
}
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
function copyResults() {
var mainResult = document.getElementById("mainResult").textContent;
var formula = document.getElementById("formulaUsed").textContent;
var weightToFat = document.getElementById("weightToFatRatio").textContent;
var fatToLean = document.getElementById("fatToLeanRatio").textContent;
var leanToFat = document.getElementById("leanToFatRatio").textContent;
var tableWeight = document.getElementById("tableWeight").textContent;
var tableFatMass = document.getElementById("tableFatMass").textContent;
var tableLeanMass = document.getElementById("tableLeanMass").textContent;
var tableBfPerc = document.getElementById("tableBfPerc").textContent;
var summary = `— Body Fat Percentage Calculation Results —\n\n`
+ `Primary Result: ${mainResult}\n`
+ `${formula}\n`
+ `\nKey Metrics:\n`
+ `${weightToFat}\n`
+ `${fatToLean}\n`
+ `${leanToFat}\n`
+ `\nBreakdown:\n`
+ `Total Body Weight: ${tableWeight} kg\n`
+ `Body Fat Mass: ${tableFatMass} kg\n`
+ `Lean Body Mass: ${tableLeanMass} kg\n`
+ `Body Fat Percentage: ${tableBfPerc}%\n`;
// Use temporary textarea to copy text
var textArea = document.createElement("textarea");
textArea.value = summary;
textArea.style.position = "fixed"; // Avoid scrolling to bottom of page in MS Edge.
textArea.style.top = 0;
textArea.style.left = 0;
textArea.style.width = '2em';
textArea.style.height = '2em';
textArea.style.padding = '0';
textArea.style.border = 'none';
textArea.style.outline = 'none';
textArea.style.boxShadow = 'none';
document.body.appendChild(textArea);
textArea.focus();
var successful = document.execCommand('copy');
document.body.removeChild(textArea);
if (successful) {
alert('Results copied to clipboard!');
} else {
alert('Failed to copy results. Please copy manually.');
}
}
// Initial chart draw setup (call it once on load if default values are present, or after first calculation)
// For now, we'll call it after calculation. Canvas rendering happens in calculateBfPercentage.
// Add interactivity to FAQ accordions
var faqItems = document.querySelectorAll('.faq-list .faq-item h4');
for (var i = 0; i 0 ? container.offsetHeight : 200; // Default height if container is too small
// Redraw chart if data exists
var bodyFatKg = parseFloat(document.getElementById("bodyFatKg").value);
var leanBodyMassKg = parseFloat(document.getElementById("leanBodyMassKg").value);
if (!isNaN(bodyFatKg) && !isNaN(leanBodyMassKg) && document.getElementById("result").style.display === 'block') {
drawBasicCanvasChart(bodyFatKg, leanBodyMassKg);
}
}
}
window.addEventListener('resize', resizeCanvas);
// Initial call to set size
window.addEventListener('load', resizeCanvas);