Understanding your body fat percentage is a key indicator of overall health and fitness, often providing a more accurate picture than just body weight or Body Mass Index (BMI). Body fat is essential for bodily functions, but too much can increase the risk of various health issues, while too little can also be detrimental.
What is Body Fat Percentage?
Body fat percentage is the total mass of fat divided by total body mass, multiplied by 100. It includes both essential fat (necessary for survival) and storage fat (accumulated fat). Healthy ranges vary significantly based on age, gender, and activity level.
Why Calculate Your Body Fat?
Health Assessment: High body fat is linked to conditions like heart disease, diabetes, and high blood pressure.
Fitness Tracking: It's a better metric for progress than scale weight, especially when building muscle.
Goal Setting: Helps in setting realistic and healthy body composition goals.
How is Body Fat Measured?
There are several methods to estimate body fat, ranging from highly accurate lab tests to more accessible home methods:
DEXA Scan (Dual-energy X-ray Absorptiometry): Considered one of the most accurate methods, providing detailed body composition analysis.
Hydrostatic Weighing (Underwater Weighing): Another highly accurate lab method based on body density.
Bioelectrical Impedance Analysis (BIA): Uses a small electrical current to estimate body fat, often found in smart scales. Accuracy can vary.
Skinfold Calipers: Measures the thickness of skinfolds at various sites on the body. Requires skill for accurate results.
Circumference Measurements (e.g., U.S. Navy Method): Uses body measurements like waist, neck, and hip to estimate body fat. This method is practical for home use and is the basis for the calculator below.
About the U.S. Navy Body Fat Calculator
The calculator below uses the U.S. Navy Body Fat Formula, a widely recognized method that relies on simple circumference measurements. While not as precise as a DEXA scan, it provides a reasonable estimate and is a good tool for tracking changes over time. It's important to take measurements consistently and accurately for the best results.
Measurement Guidelines:
Height: Stand tall without shoes, measure from the top of your head to the floor.
Neck: Measure just below the larynx (Adam's apple), keeping the tape parallel to the floor.
Waist (Men): Measure horizontally at the navel.
Waist (Women): Measure horizontally at the narrowest point of your natural waist, usually above the navel.
Hip (Women Only): Measure horizontally at the widest part of your hips.
Take all measurements with a flexible tape measure, ensuring it's snug but not compressing the skin. For best consistency, take measurements three times and use the average.
Body Fat Percentage Calculator
Use the U.S. Navy Body Fat Formula to estimate your body fat percentage.
function toggleHipInput() {
var genderFemale = document.getElementById('genderFemale');
var hipInputGroup = document.getElementById('hipInputGroup');
if (genderFemale.checked) {
hipInputGroup.style.display = 'block';
} else {
hipInputGroup.style.display = 'none';
document.getElementById('hipInput').value = ";
}
}
function updateUnitLabels() {
var unitInches = document.getElementById('unitInches');
var unitText = unitInches.checked ? 'inches' : 'cm';
document.getElementById('heightLabel').innerText = 'Height (' + unitText + '):';
document.getElementById('neckLabel').innerText = 'Neck Circumference (' + unitText + '):';
document.getElementById('waistLabel').innerText = 'Waist Circumference (' + unitText + '):';
document.getElementById('hipLabel').innerText = 'Hip Circumference (' + unitText + '):';
}
toggleHipInput();
updateUnitLabels();
function calculateBodyFat() {
var genderMale = document.getElementById('genderMale').checked;
var genderFemale = document.getElementById('genderFemale').checked;
var unitInches = document.getElementById('unitInches').checked;
var height = parseFloat(document.getElementById('heightInput').value);
var neck = parseFloat(document.getElementById('neckInput').value);
var waist = parseFloat(document.getElementById('waistInput').value);
var hip = parseFloat(document.getElementById('hipInput').value);
var resultDiv = document.getElementById('result');
resultDiv.innerHTML = ";
if (isNaN(height) || height <= 0 || isNaN(neck) || neck <= 0 || isNaN(waist) || waist <= 0) {
resultDiv.innerHTML = 'Please enter valid positive numbers for all required measurements.';
return;
}
if (genderFemale && (isNaN(hip) || hip <= 0)) {
resultDiv.innerHTML = 'Please enter a valid positive number for Hip Circumference for females.';
return;
}
var conversionFactor = 1;
if (!unitInches) {
conversionFactor = 0.393701;
}
height *= conversionFactor;
neck *= conversionFactor;
waist *= conversionFactor;
if (genderFemale) {
hip *= conversionFactor;
}
var bodyFatPercentage;
if (genderMale) {
var term1 = Math.log10(waist – neck);
var term2 = Math.log10(height);
if (isNaN(term1) || (waist – neck) <= 0) {
resultDiv.innerHTML = 'Waist circumference must be greater than neck circumference for men.';
return;
}
var denominator = 1.0324 – (0.19077 * term1) + (0.15456 * term2);
bodyFatPercentage = (495 / denominator) – 450;
} else if (genderFemale) {
var term1 = Math.log10(waist + hip – neck);
var term2 = Math.log10(height);
if (isNaN(term1) || (waist + hip – neck) <= 0) {
resultDiv.innerHTML = 'The sum of waist and hip circumference must be greater than neck circumference for women.';
return;
}
var denominator = 1.29579 – (0.35004 * term1) + (0.22100 * term2);
bodyFatPercentage = (495 / denominator) – 450;
}
if (isNaN(bodyFatPercentage) || bodyFatPercentage < 0) {
resultDiv.innerHTML = 'Could not calculate body fat percentage. Please check your measurements. Results might be outside typical ranges for this formula.';
return;
}
resultDiv.innerHTML = '