.bf-calc-wrapper { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif; max-width: 800px; margin: 20px auto; padding: 25px; border: 1px solid #e1e1e1; border-radius: 12px; background-color: #ffffff; box-shadow: 0 4px 15px rgba(0,0,0,0.05); }
.bf-calc-header { text-align: center; margin-bottom: 30px; }
.bf-calc-header h2 { color: #2c3e50; margin-bottom: 10px; font-size: 28px; }
.bf-calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 25px; }
.bf-input-group { margin-bottom: 15px; }
.bf-input-group label { display: block; margin-bottom: 8px; font-weight: 600; color: #444; font-size: 14px; }
.bf-input-group input, .bf-input-group select { width: 100%; padding: 12px; border: 1px solid #ccc; border-radius: 6px; box-sizing: border-box; font-size: 16px; transition: border-color 0.3s; }
.bf-input-group input:focus { border-color: #3498db; outline: none; box-shadow: 0 0 5px rgba(52,152,219,0.2); }
.bf-radio-group { display: flex; gap: 15px; padding: 10px 0; }
.bf-radio-option { display: flex; align-items: center; gap: 5px; cursor: pointer; }
.bf-btn { background-color: #27ae60; color: white; border: none; padding: 15px 30px; font-size: 18px; font-weight: bold; border-radius: 6px; cursor: pointer; width: 100%; transition: background 0.3s; }
.bf-btn:hover { background-color: #219150; }
.bf-result-box { margin-top: 25px; padding: 20px; border-radius: 8px; text-align: center; display: none; }
.bf-result-value { font-size: 32px; font-weight: 800; color: #2c3e50; margin-bottom: 10px; }
.bf-result-category { font-size: 18px; font-weight: 600; text-transform: uppercase; letter-spacing: 1px; }
.bf-article { margin-top: 40px; line-height: 1.7; color: #333; }
.bf-article h2 { color: #2c3e50; border-bottom: 2px solid #27ae60; padding-bottom: 10px; margin-top: 30px; }
.bf-article h3 { color: #2c3e50; margin-top: 25px; }
.bf-table { width: 100%; border-collapse: collapse; margin: 20px 0; font-size: 14px; }
.bf-table th, .bf-table td { border: 1px solid #ddd; padding: 12px; text-align: left; }
.bf-table th { background-color: #f8f9fa; }
.bf-tips { background-color: #f1f9ff; padding: 20px; border-left: 5px solid #3498db; margin: 20px 0; border-radius: 0 8px 8px 0; }
@media (max-width: 600px) { .bf-calc-grid { grid-template-columns: 1fr; } }
Unit System
Metric (cm, kg)
Imperial (in, lbs)
Height (cm)
Neck Circumference (cm)
Waist Circumference (cm)
Hip Circumference (cm)
CALCULATE BODY FAT
Understanding Body Fat Percentage
Body fat percentage is a measurement that identifies the total mass of fat divided by total body mass, multiplied by 100. Unlike Body Mass Index (BMI), which only uses height and weight, body fat percentage distinguishes between muscle mass and fat mass, making it a more accurate health marker for athletes and fitness enthusiasts.
How the Navy Method Works
The U.S. Navy Method is a widely accepted formula for estimating body composition without expensive clinical equipment like DXA scans. It uses specific circumference measurements to estimate volume and density:
For Men: Measured at the neck and the waist (at the navel).For Women: Measured at the neck, the waist (narrowest point), and the hips (widest point).
Pro Tip: For the most accurate results, use a flexible non-stretchable tape measure. Measure in the morning before eating and ensure the tape is level and snug against the skin without compressing the soft tissue.
Body Fat Categories (ACE Standards)
Category
Women Range
Men Range
Essential Fat 10-13% 2-5% Athletes 14-20% 6-13% Fitness 21-24% 14-17% Average 25-31% 18-24% Obese 32%+ 25%+
Example Calculation
Suppose a male individual has a height of 180 cm, a neck circumference of 40 cm, and a waist of 90 cm. Using the Navy Formula:
Formula: 495 / (1.0324 – 0.19077 * log10(Waist – Neck) + 0.15456 * log10(Height)) – 450
The result would be approximately 17.6% , placing him in the "Fitness" category.
function toggleUnits() {
var units = document.getElementById('units').value;
var labels = {
metric: { h: 'Height (cm)', n: 'Neck Circumference (cm)', w: 'Waist Circumference (cm)', hi: 'Hip Circumference (cm)' },
imperial: { h: 'Height (inches)', n: 'Neck Circumference (inches)', w: 'Waist Circumference (inches)', hi: 'Hip Circumference (inches)' }
};
document.getElementById('labelHeight').innerText = labels[units].h;
document.getElementById('labelNeck').innerText = labels[units].n;
document.getElementById('labelWaist').innerText = labels[units].w;
document.getElementById('labelHips').innerText = labels[units].hi;
}
function toggleHips() {
var gender = document.querySelector('input[name="gender"]:checked').value;
var hipGroup = document.getElementById('hipGroup');
hipGroup.style.display = (gender === 'female') ? 'block' : 'none';
}
function calculateBF() {
var units = document.getElementById('units').value;
var gender = document.querySelector('input[name="gender"]:checked').value;
var h = parseFloat(document.getElementById('bfHeight').value);
var n = parseFloat(document.getElementById('bfNeck').value);
var w = parseFloat(document.getElementById('bfWaist').value);
var hi = parseFloat(document.getElementById('bfHips').value) || 0;
if (!h || !n || !w || (gender === 'female' && !hi)) {
alert('Please enter all required measurements.');
return;
}
// Convert to Metric for calculation (cm)
if (units === 'imperial') {
h = h * 2.54;
n = n * 2.54;
w = w * 2.54;
hi = hi * 2.54;
}
var bodyFat = 0;
if (gender === 'male') {
// Navy Formula for Men
bodyFat = 495 / (1.0324 – 0.19077 * Math.log10(w – n) + 0.15456 * Math.log10(h)) – 450;
} else {
// Navy Formula for Women
bodyFat = 495 / (1.29579 – 0.35004 * Math.log10(w + hi – n) + 0.22100 * Math.log10(h)) – 450;
}
if (isNaN(bodyFat) || bodyFat < 0) {
alert('Calculation error. Please check your measurements (Waist must be larger than neck).');
return;
}
displayResults(bodyFat, gender);
}
function displayResults(bf, gender) {
var resultBox = document.getElementById('bfResult');
var bfValue = document.getElementById('bfValue');
var bfCategory = document.getElementById('bfCategory');
bfValue.innerText = bf.toFixed(1) + '%';
resultBox.style.display = 'block';
var category = "";
var bgColor = "";
if (gender === 'male') {
if (bf < 6) { category = "Essential Fat"; bgColor = "#e1f5fe"; }
else if (bf < 14) { category = "Athlete"; bgColor = "#c8e6c9"; }
else if (bf < 18) { category = "Fitness"; bgColor = "#dcedc8"; }
else if (bf < 25) { category = "Average"; bgColor = "#fff9c4"; }
else { category = "Obese"; bgColor = "#ffccbc"; }
} else {
if (bf < 14) { category = "Essential Fat"; bgColor = "#e1f5fe"; }
else if (bf < 21) { category = "Athlete"; bgColor = "#c8e6c9"; }
else if (bf < 25) { category = "Fitness"; bgColor = "#dcedc8"; }
else if (bf < 32) { category = "Average"; bgColor = "#fff9c4"; }
else { category = "Obese"; bgColor = "#ffccbc"; }
}
bfCategory.innerText = category;
resultBox.style.backgroundColor = bgColor;
}