Enter your measurements for an estimated body fat percentage.
Male
Female
–.–% Body Fat
Understanding Body Fat Percentage Calculation
Body Fat Percentage (BFP) is a measure of fat in relation to total body mass. It's a crucial indicator of health, as both excessively high and low body fat can pose risks. This calculator uses common formulas to estimate BFP based on your provided measurements.
Methods Used:
This calculator primarily employs the U.S. Navy Circumference Method, which is a widely recognized and relatively accessible way to estimate body fat without specialized equipment. For males, it uses weight, height, neck, and waist circumference. For females, it uses weight, height, neck, waist, and hip circumference.
2. Calculate Body Fat Percentage:
BFP = 495 / (1.0324 – 0.19077 * log10(Waist – Neck) + 0.15456 * log10(Height)) – 450
*Note: Some variations of the Navy method use a slightly different formula, and may integrate BMI. For simplicity and common usage, the circumference-based formula is applied here.*
2. Calculate Body Fat Percentage:
BFP = 495 / (1.29579 – 0.35004 * log10(Waist + Hip – Neck) + 0.22100 * log10(Height)) – 450
*Note: Similar to males, variations exist. The formula used here is standard for the Navy method.*
Measurement Tips:
Weight: Use a calibrated scale.
Height: Stand straight against a wall, mark the top of your head, and measure.
Circumferences: Use a flexible tape measure. Measure at the narrowest point for neck (base of larynx), narrowest point for waist (above navel, below ribs), widest point for hips (over buttocks). Ensure the tape is snug but not digging in.
Consistency: Take measurements at the same time of day, under similar conditions, for accurate tracking.
Interpreting Results:
Body fat percentages vary by age and sex. Generally:
Athletes: Men: 6-13%, Women: 14-20%
Fitness: Men: 14-17%, Women: 21-24%
Average: Men: 18-24%, Women: 25-31%
Obese: Men: 25%+, Women: 32%+
This calculator provides an estimate. For precise measurements, consult a healthcare professional or a certified fitness trainer.
function getElement(id) {
return document.getElementById(id);
}
function calculateBodyFat() {
var gender = getElement("gender").value;
var weightKg = parseFloat(getElement("weightKg").value);
var heightCm = parseFloat(getElement("heightCm").value);
var age = parseFloat(getElement("age").value);
var waistCm = parseFloat(getElement("waistCm").value);
var neckCm = parseFloat(getElement("neckCm").value);
var hipCm = parseFloat(getElement("hipCm").value);
var resultValueElement = getElement("resultValue");
if (isNaN(weightKg) || isNaN(heightCm) || isNaN(age) || isNaN(waistCm) || isNaN(neckCm) || (gender === "female" && isNaN(hipCm))) {
resultValueElement.innerText = "Invalid Input";
return;
}
var heightM = heightCm / 100;
var bodyFat = 0;
if (gender === "male") {
getElement("hipGroup").style.display = 'none';
var waistMinusNeck = waistCm – neckCm;
if (waistMinusNeck <= 0 || heightM <= 0) {
resultValueElement.innerText = "Invalid Measurement";
return;
}
bodyFat = 495 / (1.0324 – 0.19077 * Math.log(waistMinusNeck) / Math.log(10) + 0.15456 * Math.log(heightM) / Math.log(10)) – 450;
} else { // female
getElement("hipGroup").style.display = 'block';
var waistHipNeck = waistCm + hipCm – neckCm;
if (waistHipNeck <= 0 || heightM <= 0) {
resultValueElement.innerText = "Invalid Measurement";
return;
}
bodyFat = 495 / (1.29579 – 0.35004 * Math.log(waistHipNeck) / Math.log(10) + 0.22100 * Math.log(heightM) / Math.log(10)) – 450;
}
// Add age adjustment if needed – often this method is age-independent, but some sources add slight adjustments.
// For simplicity, sticking to the core Navy method.
if (bodyFat 100) { // Prevent results over 100%
bodyFat = 100;
}
resultValueElement.innerText = bodyFat.toFixed(2);
}
// Initialize gender-specific display
document.addEventListener("DOMContentLoaded", function() {
var genderSelect = getElement("gender");
var hipGroup = getElement("hipGroup");
if (genderSelect.value === "male") {
hipGroup.style.display = 'none';
} else {
hipGroup.style.display = 'block';
}
genderSelect.addEventListener("change", function() {
if (this.value === "male") {
hipGroup.style.display = 'none';
} else {
hipGroup.style.display = 'block';
}
});
});