Body Fat Percentage Calculator
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f8f9fa;
color: #333;
line-height: 1.6;
margin: 0;
padding: 20px;
}
.calculator-container {
max-width: 700px;
margin: 30px auto;
background-color: #fff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}
h1, h2 {
color: #004a99;
text-align: center;
margin-bottom: 20px;
}
.input-group {
margin-bottom: 20px;
display: flex;
flex-direction: column;
align-items: flex-start;
}
.input-group label {
margin-bottom: 8px;
font-weight: bold;
color: #004a99;
}
.input-group input[type="number"],
.input-group select {
width: calc(100% – 20px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
font-size: 1rem;
}
button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #004a99;
color: white;
border: none;
border-radius: 4px;
font-size: 1.1rem;
cursor: pointer;
transition: background-color 0.3s ease;
margin-top: 10px;
}
button:hover {
background-color: #003366;
}
#result {
margin-top: 30px;
padding: 20px;
background-color: #e7f3ff;
border-left: 5px solid #004a99;
border-radius: 4px;
text-align: center;
}
#result p {
margin: 0 0 10px 0;
font-size: 1.2rem;
}
#result span {
font-size: 2.5rem;
font-weight: bold;
color: #28a745;
}
.explanation {
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padding: 30px;
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border-radius: 8px;
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.explanation h2 {
color: #004a99;
text-align: left;
margin-bottom: 15px;
}
.explanation p, .explanation ul {
color: #555;
margin-bottom: 15px;
}
.explanation li {
margin-bottom: 10px;
}
@media (max-width: 600px) {
.calculator-container {
padding: 20px;
}
button {
font-size: 1rem;
}
#result span {
font-size: 2rem;
}
}
Body Fat Percentage Calculator
Estimate your body fat percentage using common measurements.
Your Estimated Body Fat Percentage:
–.– %
Understanding Body Fat Percentage
Body fat percentage is a measure of how much of your body mass is made up of fat. It's a more accurate indicator of health and fitness than simple weight or BMI alone, as it distinguishes between fat mass and lean body mass (muscles, bones, organs, water).
How This Calculator Works (US Navy Method)
This calculator uses the widely accepted U.S. Navy Body Fat formula. It's a simple yet effective method that requires only a few body measurements. The core idea is to use the circumference measurements in relation to height to estimate body density.
Formulas Used:
- For Men: Body Fat % = 495 / (1.0324 – 0.19077 * log10(Waist – Neck) + 0.15456 * log10(Height)) – 450
- For Women: Body Fat % = 495 / (1.29579 – 0.13723 * log10(Hip + Waist – Neck) + 0.05264 * log10(Height)) – 450
Note: In these formulas, circumference measurements (Waist, Neck, Hip) and Height are typically measured in inches. This calculator converts your metric inputs (cm) to inches internally for the calculation.
Measurement Guidelines:
- Weight: Weigh yourself on a scale, preferably in the morning after using the restroom.
- Height: Stand against a wall without shoes, with your feet flat on the floor.
- Neck: Measure the circumference at the base of your neck, just below the larynx.
- Waist: For men, measure at the navel level. For women, measure at the narrowest part of your torso, typically above the hip bones.
- Hip (Women only): Measure the circumference around the widest part of your hips/buttocks.
Interpreting Your Results
Body fat percentage ranges vary significantly by age and sex. Here are general guidelines:
General Healthy Ranges (approximate):
- Men: 15-20%
- Women: 20-25%
Athletes: Typically have lower body fat percentages.
Higher percentages may indicate an increased risk for certain health conditions. It's always recommended to consult with a healthcare professional for personalized advice regarding your body composition and health goals.
function calculateBodyFat() {
var gender = document.getElementById("gender").value;
var weightKg = parseFloat(document.getElementById("weightKg").value);
var heightCm = parseFloat(document.getElementById("heightCm").value);
var neckCm = parseFloat(document.getElementById("neckCm").value);
var waistCm = parseFloat(document.getElementById("waistCm").value);
var hipCm = parseFloat(document.getElementById("hipCm").value);
var resultElement = document.getElementById("bodyFatResult");
var hipGroup = document.getElementById("hipGroup");
// Show/hide hip measurement based on gender
if (gender === "male") {
hipGroup.style.display = "none";
} else {
hipGroup.style.display = "flex";
}
// Basic validation
if (isNaN(weightKg) || isNaN(heightCm) || isNaN(neckCm) || isNaN(waistCm) || (gender === "female" && isNaN(hipCm))) {
resultElement.textContent = "Invalid input";
return;
}
// Convert cm to inches (1 inch = 2.54 cm)
var heightIn = heightCm / 2.54;
var neckIn = neckCm / 2.54;
var waistIn = waistCm / 2.54;
var hipIn = hipCm / 2.54;
var bodyFatPercentage;
if (gender === "male") {
// US Navy formula for men
var numerator = 495;
var denominator = 1.0324 – (0.19077 * Math.log(waistIn – neckIn) / Math.log(10)) + (0.15456 * Math.log(heightIn) / Math.log(10));
bodyFatPercentage = (numerator / denominator) – 450;
} else { // female
// US Navy formula for women
var numerator = 495;
var denominator = 1.29579 – (0.13723 * Math.log(hipIn + waistIn – neckIn) / Math.log(10)) + (0.05264 * Math.log(heightIn) / Math.log(10));
bodyFatPercentage = (numerator / denominator) – 450;
}
// Ensure result is not negative (can happen with very lean individuals or measurement errors)
if (bodyFatPercentage < 0) {
bodyFatPercentage = 0;
}
resultElement.textContent = bodyFatPercentage.toFixed(1) + " %";
}
// Initial call to set hip visibility based on default gender
document.addEventListener('DOMContentLoaded', function() {
calculateBodyFat();
});
document.getElementById('gender').addEventListener('change', calculateBodyFat);