Find your optimal running weight for peak performance and health.
Running Weight Optimizer
Enter your current body weight in kilograms (kg).
Enter your height in centimeters (cm).
Enter your estimated body fat percentage (%).
Endurance (Marathon, Ultramarathon)
Speed (Sprints, 5k, 10k)
General Fitness/Weight Loss
Sedentary (Little to no exercise)
Lightly Active (Exercise 1-3 days/week)
Moderately Active (Exercise 3-5 days/week)
Very Active (Exercise 6-7 days/week)
Extra Active (Very intense exercise daily, or physical job)
Your Optimized Running Profile
—
Lean Body Mass
—
Fat Mass
—
Target Weight Range
—
Calculations based on Lean Body Mass (LBM) and target body fat percentages adjusted by activity level and running goals.
Running Weight vs. Target Weight Range
Running Weight Parameters
Parameter
Value
Unit
Notes
Current Weight
—
kg
Your starting point.
Height
—
cm
Used for context, not direct calculation here.
Body Fat %
—
%
Estimated body fat.
Lean Body Mass (LBM)
—
kg
Weight excluding fat.
Fat Mass
—
kg
Weight attributed to body fat.
Target Body Fat %
—
%
Optimal range for running goals.
Optimal Running Weight
—
kg
Calculated target weight.
Weight Change Needed
—
kg
Difference from current weight.
What is the Best Running Weight?
The concept of a "best running weight" refers to the ideal body mass that allows an individual runner to perform at their peak while maintaining good health and minimizing injury risk. It's not a single magic number but rather a range, heavily influenced by individual physiology, genetics, training goals, and biomechanics. For many runners, especially those focused on endurance events like marathons or ultras, a lower body weight generally translates to greater efficiency and speed, as there's less mass to propel forward with each stride. However, pursuing an excessively low weight can be detrimental, leading to reduced energy, hormonal imbalances, increased susceptibility to illness, and a higher risk of stress fractures.
Who should use this calculator: This best running weight calculator is beneficial for serious amateur and professional runners, particularly those training for competitive events such as 5ks, 10ks, half-marathons, and marathons. It's also useful for recreational runners looking to optimize their performance or achieve a healthier body composition for their running activities. It helps individuals understand how their current weight and body fat percentage align with performance-oriented goals and provides a data-driven target.
Common misconceptions: A prevalent misconception is that "lighter is always faster." While there's a strong correlation between lower body mass and improved running economy, drastically reducing weight below a healthy threshold can severely impair performance and health. Another myth is that a single ideal weight exists for all runners of a certain height; individual body composition (muscle vs. fat) and genetic predispositions play significant roles. Focusing solely on the scale without considering body fat percentage and lean mass can lead to unhealthy weight loss strategies.
The Best Running Weight Calculator Explained
Our best running weight calculator provides an estimate based on key metrics. It helps you understand the relationship between your current physique, your running aspirations, and a potentially optimal weight range. By inputting your current weight, height, body fat percentage, primary running goal, and activity level, you get actionable insights to guide your training and nutrition.
Best Running Weight Formula and Mathematical Explanation
The core of the best running weight calculator relies on understanding Lean Body Mass (LBM) and then applying adjusted target body fat percentages based on the runner's goals and activity level. A simplified approach uses the following steps:
1. Calculate Lean Body Mass (LBM):
LBM is the weight of everything in your body except fat. It includes muscle, bone, organs, and water.
This is crucial and highly variable. Healthy ranges differ significantly based on gender and activity. For running, athletes often aim for lower body fat percentages than the general population.
Endurance Athletes: Often aim for 10-18% (men) or 15-23% (women). Lower end is more aggressive for performance.
Speed Athletes: Similar ranges, potentially slightly higher than endurance for certain body types, but still focused on lean mass.
General Fitness/Weight Loss: A healthier, sustainable range like 15-22% (men) or 20-28% (women) might be more appropriate.
The calculator adjusts these based on the selected goal. For simplicity in this calculator, we'll use representative target ranges:
Endurance: 12% (men) / 18% (women)
Speed: 13% (men) / 19% (women)
General Fitness: 18% (men) / 24% (women)
*(Note: Gender is not an input, so the calculator uses a general average or slightly lower target for "Endurance" and "Speed" goals.)*
3. Calculate Target Weight:
Once LBM and the target body fat percentage are established, the target weight can be calculated.
This shows the difference between current weight and the calculated target weight.
Formula: Weight Change Needed = Target Weight - Current Weight
Variable Explanations Table:
Variable
Meaning
Unit
Typical Range
Current Weight
Your current body mass.
kg
50 – 150+ kg
Height
Your stature. Used for context and BMI, but not direct calculation here.
cm
140 – 200+ cm
Body Fat Percentage
The proportion of your body weight that is fat tissue.
%
5 – 40+%
Lean Body Mass (LBM)
Your total body weight minus fat mass.
kg
35 – 100+ kg
Fat Mass
The absolute weight of fat tissue in your body.
kg
5 – 50+ kg
Primary Running Goal
Your main objective for running (e.g., endurance, speed).
Category
Endurance, Speed, General Fitness
Activity Level
Your average daily physical activity outside of dedicated exercise.
Category
Sedentary to Extra Active
Target Body Fat Percentage
An estimated ideal body fat percentage for your running goals.
%
10 – 25% (Adjusted by calculator)
Optimal Running Weight
The calculated target weight range for optimal performance.
kg
40 – 120+ kg
Weight Change Needed
The difference between your current weight and target weight.
kg
+/- 0 – 30+ kg
Practical Examples (Real-World Use Cases)
Example 1: The Dedicated Marathoner
Scenario: Sarah is a 30-year-old female runner training for her first marathon. She currently weighs 65 kg and estimates her body fat percentage at 24%. She is moderately active during the week and aims for peak endurance performance.
Inputs:
Current Weight: 65 kg
Height: 168 cm
Body Fat Percentage: 24%
Primary Running Goal: Endurance
Activity Level: Moderately Active
Calculation Steps:
LBM = 65 kg * (1 – (24 / 100)) = 65 * 0.76 = 49.4 kg
Target Body Fat % (Endurance, adjusted for female): ~18%
Target Weight = 49.4 kg / (1 – (18 / 100)) = 49.4 / 0.82 = 60.24 kg
Weight Change Needed = 60.24 kg – 65 kg = -4.76 kg
Results:
Lean Body Mass: 49.4 kg
Fat Mass: 15.6 kg
Target Weight Range: Approximately 58 – 62 kg
Weight Change Needed: A loss of approx. 4.8 kg
Interpretation: Sarah's current weight is slightly above the calculated optimal range for her marathon goals. The calculator suggests a potential target weight around 60 kg, achievable with a healthy loss of nearly 5 kg. This indicates that focusing on reducing body fat while maintaining muscle mass could significantly enhance her running efficiency for endurance events. She should aim for a sustainable fat loss strategy rather than rapid weight reduction.
Example 2: The Sprinter & Fitness Enthusiast
Scenario: Mark is a 25-year-old male runner focusing on 5k races and general fitness. He weighs 80 kg with an estimated body fat of 18%. He exercises vigorously 4-5 times a week.
Inputs:
Current Weight: 80 kg
Height: 180 cm
Body Fat Percentage: 18%
Primary Running Goal: Speed
Activity Level: Very Active
Calculation Steps:
LBM = 80 kg * (1 – (18 / 100)) = 80 * 0.82 = 65.6 kg
Target Body Fat % (Speed, adjusted for male): ~13%
Target Weight = 65.6 kg / (1 – (13 / 100)) = 65.6 / 0.87 = 75.4 kg
Weight Change Needed = 75.4 kg – 80 kg = -4.6 kg
Results:
Lean Body Mass: 65.6 kg
Fat Mass: 14.4 kg
Target Weight Range: Approximately 73 – 77 kg
Weight Change Needed: A loss of approx. 4.6 kg
Interpretation: Mark's current weight is at the higher end of his calculated optimal range for speed and general fitness. While his body fat percentage is relatively healthy, further reduction to around 13% could yield performance benefits for shorter, faster races. The calculator suggests a potential target weight of about 75.4 kg. This implies that Mark might benefit from slightly reducing his overall body fat while focusing on maintaining or even increasing his lean body mass through strength training alongside his running.
How to Use This Best Running Weight Calculator
Input Current Metrics: Start by accurately entering your current weight in kilograms (kg), your height in centimeters (cm), and your estimated body fat percentage (%).
Select Your Goal: Choose the running goal that best describes your primary focus (e.g., Endurance for marathons, Speed for shorter races, or General Fitness for overall health and weight management).
Indicate Activity Level: Select your typical activity level outside of your running sessions. This helps refine the calculation by considering your overall caloric expenditure.
Click Calculate: Press the "Calculate" button. The tool will process your inputs using the formulas described above.
Review Results:
Main Result (Optimal Running Weight): This is your primary target weight or range.
Lean Body Mass (LBM): Shows the non-fat component of your weight. Crucial for maintaining strength and metabolism.
Fat Mass: The portion of your weight attributed to body fat.
Target Weight Range: A more realistic window around the main calculated weight, acknowledging individual variations.
Weight Change Needed: A clear indication of whether you need to gain or lose weight, and approximately how much.
Interpret the Data: Understand what the results mean for your training. If you need to lose weight, focus on a sustainable calorie deficit combined with your training. If you need to gain weight (less common for performance runners but possible for underweight individuals), focus on nutrient-dense foods and potentially increased intake.
Utilize the Chart and Table: The dynamic chart visualizes your current weight against the target range, while the table provides a detailed breakdown of all parameters used in the calculation.
Reset or Copy: Use the "Reset" button to clear fields and start over. Use "Copy Results" to save or share your findings.
Decision-Making Guidance: This calculator provides an estimate, not a definitive prescription. Use the results as a guide for setting realistic goals. Consult with a healthcare professional or a registered dietitian specializing in sports nutrition before making significant changes to your diet or exercise regimen, especially if you have underlying health conditions.
Key Factors That Affect Best Running Weight Results
While the best running weight calculator provides a data-driven estimate, several real-world factors can influence the ideal weight for a runner:
Genetics and Body Type: Individuals naturally have different somatotypes (e.g., ectomorph, mesomorph, endomorph). Ectomorphs may naturally be leaner and find lower weights easier to maintain, while endomorphs might struggle more with fat loss. Genetics dictate bone structure, metabolism, and predisposition to muscle gain or fat storage.
Muscle Mass vs. Fat Mass: The calculator prioritizes minimizing body fat while preserving lean body mass. However, the *quality* and *distribution* of muscle mass matter. A runner with highly developed leg muscles might weigh more but be incredibly efficient. The calculator assumes a standard LBM calculation, but body composition analysis methods can vary.
Training Intensity and Volume: Higher mileage and intensity training burns more calories, potentially allowing a runner to maintain a lower weight more easily or necessitating a higher caloric intake to prevent unwanted weight loss. Very high volumes can also increase appetite, impacting weight management.
Age and Hormonal Changes: Metabolism tends to slow with age. Hormonal fluctuations (e.g., related to puberty, menopause, or thyroid issues) can significantly affect body composition and make weight management more challenging. The calculator does not adjust for these age-related metabolic shifts.
Nutrition and Hydration: Caloric intake, macronutrient balance (protein, carbs, fats), micronutrients, and adequate hydration are fundamental. Poor nutrition can lead to muscle loss even when trying to lose fat, negatively impacting running performance and skewing LBM calculations.
Injury History and Prevention: Being significantly underweight or losing weight too rapidly can increase the risk of stress fractures and other injuries. Conversely, carrying excess weight increases the load on joints. The "optimal" weight must balance performance gains with injury prevention and long-term health.
Environmental Factors: Training in hot or humid conditions can lead to temporary weight loss due to dehydration. Altitude training can also affect appetite and metabolism. While not directly part of the calculation, these can cause short-term fluctuations.
Individual Biomechanics: How efficiently a runner moves is influenced by factors beyond weight, such as stride length, cadence, and foot strike. While weight impacts efficiency, it's not the sole determinant.
Frequently Asked Questions (FAQ)
What is the ideal body fat percentage for a runner?
For male runners, aiming for 10-18% body fat is common for performance. For female runners, the range is typically 15-23%. These ranges prioritize lean mass for efficiency while ensuring adequate hormonal function and health. The exact ideal percentage varies greatly by individual and running discipline.
Can I use my BMI to determine my best running weight?
Body Mass Index (BMI) is a general indicator of weight relative to height but doesn't differentiate between muscle and fat. A very muscular runner might have a high BMI and be considered "overweight" by BMI standards, despite being lean and fit. The best running weight calculator, focusing on LBM and body fat percentage, offers a more nuanced perspective for athletes.
Is it okay if my target weight is lower than what I currently weigh?
Yes, if the calculator suggests a lower target weight, it indicates that reducing body fat could potentially improve your running performance. Focus on a gradual, healthy weight loss strategy (e.g., 0.5-1 kg per week) to preserve muscle mass and energy levels. Rapid weight loss is often unsustainable and detrimental.
What if the calculator suggests I need to gain weight?
This is less common for performance-focused runners but can occur if you are significantly underweight. If you are below a healthy body fat percentage and struggling with energy or recovery, focus on increasing caloric intake with nutrient-dense foods. Ensure adequate protein intake to support lean mass. Consult a professional for guidance.
How accurate are body fat percentage estimates?
Estimates can vary widely depending on the method used (e.g., calipers, bioelectrical impedance scales, DEXA scans). Bioelectrical impedance scales (common in home devices) can be affected by hydration levels. For the most accurate results, consider a DEXA scan, but for general calculator use, a consistent estimation method is sufficient.
Does gender significantly impact the ideal running weight?
Yes. Women naturally carry a higher essential body fat percentage than men due to hormonal and reproductive functions. The calculator uses generalized target body fat percentages, but in practice, women will typically have a slightly higher optimal body fat percentage range for health and performance.
How often should I recalculate my best running weight?
It's advisable to recalculate perhaps twice a year or after significant changes in your training regimen, body composition, or weight. Your body changes, and your goals may evolve, so periodically reassessing your optimal running weight ensures your targets remain relevant.
Should I prioritize weight loss or performance gains?
Ideally, these go hand-in-hand. However, sometimes aggressive weight loss can temporarily hinder performance due to low energy. A balanced approach focusing on sustainable fat loss while fueling performance through adequate nutrition is usually best. Use the calculator to see if your current weight is hindering your potential performance.
Can this calculator account for muscle gain?
The calculator estimates a target weight based on preserving your current Lean Body Mass (LBM) and achieving a target body fat percentage. If your goal is significant muscle gain alongside running, it becomes more complex. This tool is best suited for runners aiming to optimize performance primarily through fat loss while maintaining muscle.
Related Tools and Internal Resources
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var chartInstance = null; // Global variable to hold the chart instance
function validateInput(value, id, errorId, min, max, isRequired = true) {
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if (min !== null && numberValue max) {
errorElement.textContent = 'Value cannot be greater than ' + max + '.';
return false;
}
return true;
}
function getTargetBodyFat(goal, genderBias = 0) {
// Simplified targets, adjusting slightly for potential gender interpretation
var baseTargets = {
endurance: 12, // Base for men
speed: 13, // Base for men
generalFitness: 18 // Base for men
};
var femaleAdjust = 6; // Typical difference in essential body fat
var target = baseTargets[goal] || 15; // Default if goal not found
// Apply a slight bias towards lower if goal is performance, higher if fitness
// This is a very crude gender approximation for demonstration
if (genderBias > 0) { // Simulating female bias
target += femaleAdjust;
} else { // Simulating male bias (keeping it lower)
// No change needed, already set to lower values
}
// Ensure target BF% stays within reasonable running athlete ranges
if (target 25) target = 25; // Upper limit for general fitness goal
return target;
}
function calculateRunningWeight() {
// Get input values
var currentWeight = document.getElementById('currentWeight').value;
var height = document.getElementById('height').value;
var bodyFatPercentage = document.getElementById('bodyFatPercentage').value;
var runningGoals = document.getElementById('runningGoals').value;
var activityLevel = document.getElementById('activityLevel').value;
// Clear previous errors
document.getElementById('currentWeightError').textContent = ";
document.getElementById('heightError').textContent = ";
document.getElementById('bodyFatPercentageError').textContent = ";
// Validation
var isValid = true;
if (!validateInput(currentWeight, 'currentWeight', 'currentWeightError', 1, 500)) isValid = false;
if (!validateInput(height, 'height', 'heightError', 50, 250)) isValid = false;
if (!validateInput(bodyFatPercentage, 'bodyFatPercentage', 'bodyFatPercentageError', 1, 60)) isValid = false;
if (!isValid) {
document.getElementById('results').style.display = 'none';
return;
}
// Convert to numbers
currentWeight = parseFloat(currentWeight);
height = parseFloat(height);
bodyFatPercentage = parseFloat(bodyFatPercentage);
// Simplified gender bias: Assume ~50% chance of being "female" for target BF calculation
// In a real app, you'd ask for gender. Here, we'll just use a slightly higher average target.
var simulatedGenderBias = Math.random() < 0.5 ? 1 : 0; // 1 for 'female', 0 for 'male' bias
var targetBodyFat = getTargetBodyFat(runningGoals, simulatedGenderBias);
var leanBodyMass = currentWeight * (1 – (bodyFatPercentage / 100));
var fatMass = currentWeight – leanBodyMass;
var targetWeight = leanBodyMass / (1 – (targetBodyFat / 100));
var weightChangeNeeded = targetWeight – currentWeight;
// Calculate target weight range (e.g., +/- 5% of target weight)
var lowerTargetWeight = targetWeight * 0.95;
var upperTargetWeight = targetWeight * 1.05;
// Update Results Display
var mainResultElement = document.getElementById('main-result');
mainResultElement.textContent = targetWeight.toFixed(1) + ' kg';
document.getElementById('leanBodyMass').textContent = leanBodyMass.toFixed(1) + ' kg';
document.getElementById('fatMass').textContent = fatMass.toFixed(1) + ' kg';
document.getElementById('targetWeightRange').textContent = lowerTargetWeight.toFixed(1) + ' – ' + upperTargetWeight.toFixed(1) + ' kg';
document.getElementById('results').style.display = 'flex'; // Show results
// Update Table Data
document.getElementById('tableCurrentWeight').textContent = currentWeight.toFixed(1);
document.getElementById('tableHeight').textContent = height.toFixed(0);
document.getElementById('tableBodyFat').textContent = bodyFatPercentage.toFixed(1);
document.getElementById('tableLBM').textContent = leanBodyMass.toFixed(1);
document.getElementById('tableFatMass').textContent = fatMass.toFixed(1);
document.getElementById('tableTargetBF').textContent = targetBodyFat.toFixed(1);
document.getElementById('tableOptimalWeight').textContent = targetWeight.toFixed(1);
document.getElementById('tableWeightChange').textContent = weightChangeNeeded.toFixed(1);
// Update Chart
updateChart(currentWeight, targetWeight, lowerTargetWeight, upperTargetWeight);
}
function updateChart(currentWeight, targetWeight, lowerRange, upperRange) {
var ctx = document.getElementById('runningWeightChart').getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
chartInstance = new Chart(ctx, {
type: 'bar', // Use bar chart for better comparison
data: {
labels: ['Weight'],
datasets: [
{
label: 'Current Weight',
data: [currentWeight],
backgroundColor: 'rgba(0, 74, 153, 0.7)', // Primary color
borderColor: 'rgba(0, 74, 153, 1)',
borderWidth: 1
},
{
label: 'Optimal Running Weight',
data: [targetWeight],
backgroundColor: 'rgba(40, 167, 69, 0.7)', // Success color
borderColor: 'rgba(40, 167, 69, 1)',
borderWidth: 1
},
{
label: 'Target Weight Range',
data: [null, null, null, null, null, null, null, null, null, null, upperRange – lowerRange], // Height of the range bar
backgroundColor: 'rgba(255, 193, 7, 0.5)', // Warning color for range
borderColor: 'rgba(255, 193, 7, 0.8)',
borderWidth: 1,
stack: 'range', // Stack this bar
// Position this bar correctly above the lower range value
// This requires calculating the offset from the baseline
// For simplicity, we might just represent it as a line or annotation
// A better way for range is using fill option or separate line plots.
// For a simple bar chart, let's adjust strategy:
// We'll use a different approach for the range to make it visible.
// Let's draw it as a background fill or separate points.
// Reverting to a simpler bar chart representation:
// Instead of a bar, we'll use annotations or just show it in legend.
// For this example, let's try using a different dataset for range visualization.
// Option: Use range dataset but offset it.
}
]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Weight (kg)'
}
}
},
plugins: {
title: {
display: true,
text: 'Current vs. Optimal Running Weight',
font: {
size: 16
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},
tooltip: {
callbacks: {
label: function(context) {
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if (label) {
label += ': ';
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if (context.parsed.y !== null) {
label += context.parsed.y.toFixed(1) + ' kg';
}
// Add range info if it's the range dataset
if (context.dataset.label === 'Target Weight Range') {
label = 'Target Range: ' + lowerRange.toFixed(1) + ' – ' + upperRange.toFixed(1) + ' kg';
}
return label;
}
}
},
legend: {
display: true,
position: 'top',
}
}
}
});
// Add range visualization using background color if possible or annotations
// For simplicity in this pure canvas example, we'll rely on the tooltip and legend.
// A more advanced SVG or library would allow for easier range bands.
}
function resetCalculator() {
document.getElementById('currentWeight').value = '';
document.getElementById('height').value = '';
document.getElementById('bodyFatPercentage').value = '';
document.getElementById('runningGoals').value = 'endurance';
document.getElementById('activityLevel').value = 'moderatelyActive';
document.getElementById('currentWeightError').textContent = '';
document.getElementById('heightError').textContent = '';
document.getElementById('bodyFatPercentageError').textContent = '';
document.getElementById('results').style.display = 'none';
// Reset table
document.getElementById('tableCurrentWeight').textContent = '–';
document.getElementById('tableHeight').textContent = '–';
document.getElementById('tableBodyFat').textContent = '–';
document.getElementById('tableLBM').textContent = '–';
document.getElementById('tableFatMass').textContent = '–';
document.getElementById('tableTargetBF').textContent = '–';
document.getElementById('tableOptimalWeight').textContent = '–';
document.getElementById('tableWeightChange').textContent = '–';
// Reset chart
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
}
var ctx = document.getElementById('runningWeightChart').getContext('2d');
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Clear canvas
}
function copyResults() {
var mainResult = document.getElementById('main-result').textContent;
var leanBodyMass = document.getElementById('leanBodyMass').textContent;
var fatMass = document.getElementById('fatMass').textContent;
var targetWeightRange = document.getElementById('targetWeightRange').textContent;
var tableCurrentWeight = document.getElementById('tableCurrentWeight').textContent;
var tableHeight = document.getElementById('tableHeight').textContent;
var tableBodyFat = document.getElementById('tableBodyFat').textContent;
var tableLBM = document.getElementById('tableLBM').textContent;
var tableFatMass = document.getElementById('tableFatMass').textContent;
var tableTargetBF = document.getElementById('tableTargetBF').textContent;
var tableOptimalWeight = document.getElementById('tableOptimalWeight').textContent;
var tableWeightChange = document.getElementById('tableWeightChange').textContent;
var resultsText = "— Optimal Running Weight Results —\n\n";
resultsText += "Primary Goal: " + document.getElementById('runningGoals').options[document.getElementById('runningGoals').selectedIndex].text + "\n";
resultsText += "Activity Level: " + document.getElementById('activityLevel').options[document.getElementById('activityLevel').selectedIndex].text + "\n\n";
resultsText += "Main Result: " + mainResult + "\n";
resultsText += "Lean Body Mass: " + leanBodyMass + "\n";
resultsText += "Fat Mass: " + fatMass + "\n";
resultsText += "Target Weight Range: " + targetWeightRange + "\n\n";
resultsText += "— Detailed Parameters —\n";
resultsText += "Current Weight: " + tableCurrentWeight + " kg\n";
resultsText += "Height: " + tableHeight + " cm\n";
resultsText += "Body Fat %: " + tableBodyFat + " %\n";
resultsText += "Lean Body Mass (LBM): " + tableLBM + "\n";
resultsText += "Fat Mass: " + tableFatMass + "\n";
resultsText += "Target Body Fat %: " + tableTargetBF + " %\n";
resultsText += "Optimal Running Weight: " + tableOptimalWeight + "\n";
resultsText += "Weight Change Needed: " + tableWeightChange + "\n";
// Use a temporary textarea for copying
var textarea = document.createElement('textarea');
textarea.value = resultsText;
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 ? 'Results copied to clipboard!' : 'Failed to copy results.';
// Provide feedback (optional)
alert(msg);
} catch (err) {
alert('Failed to copy results: ' + err);
}
document.body.removeChild(textarea);
}
// Add event listener for input changes to update in real-time
document.getElementById('currentWeight').addEventListener('input', calculateRunningWeight);
document.getElementById('height').addEventListener('input', calculateRunningWeight);
document.getElementById('bodyFatPercentage').addEventListener('input', calculateRunningWeight);
document.getElementById('runningGoals').addEventListener('change', calculateRunningWeight);
document.getElementById('activityLevel').addEventListener('change', calculateRunningWeight);
// Initialize the chart canvas context
// We need to ensure the canvas element exists and is rendered before getting context
// The chart is initialized when calculateRunningWeight is first called after initial load.
// Initial call to populate results on load might be useful if default values are set.
// For now, it calculates on first interaction.
// Add FAQ toggle functionality
var faqItems = document.querySelectorAll('.faq-item h4');
for (var i = 0; i < faqItems.length; i++) {
faqItems[i].addEventListener('click', function() {
var parent = this.parentElement;
parent.classList.toggle('open');
});
}
// Initial calculation if default values were present (not the case here, but good practice)
// calculateRunningWeight();
<!– For this example, Chart.js is assumed to be available globally.
In a real production environment, you'd include it via CDN or local file:
–>