Calculator Fat Percentage

Body Fat Percentage Calculator

Use this calculator to estimate your body fat percentage based on the U.S. Navy Body Fat Formula. This method uses specific body measurements to provide an estimate, which can be a useful indicator of overall health and fitness.

function toggleHipInput() { var genderFemale = document.getElementById('genderFemale'); var hipGroup = document.getElementById('hipGroup'); if (genderFemale.checked) { hipGroup.style.display = 'block'; } else { hipGroup.style.display = 'none'; document.getElementById('hip').value = "; // Clear hip value if switching to male } } // Initialize hip input visibility on page load window.onload = toggleHipInput; function calculateBodyFat() { var genderMale = document.getElementById('genderMale').checked; var genderFemale = document.getElementById('genderFemale').checked; var height = parseFloat(document.getElementById('height').value); var neck = parseFloat(document.getElementById('neck').value); var waist = parseFloat(document.getElementById('waist').value); var hip = parseFloat(document.getElementById('hip').value); // Only used for females var resultDiv = document.getElementById('fatPercentageResult'); resultDiv.innerHTML = "; // Clear previous results if (isNaN(height) || isNaN(neck) || isNaN(waist) || height <= 0 || neck <= 0 || waist <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for Height, Neck, and Waist measurements.'; return; } if (genderFemale && isNaN(hip) || (genderFemale && hip <= 0)) { resultDiv.innerHTML = 'Please enter a valid positive number for Hip Circumference for females.'; return; } var bodyFatPercentage; if (genderMale) { // Men: Body Fat % = 86.010 * log10(waist – neck) – 70.041 * log10(height) + 36.76 var logWaistNeck = Math.log10(waist – neck); var logHeight = Math.log10(height); if (isNaN(logWaistNeck) || (waist – neck) <= 0) { resultDiv.innerHTML = 'Waist circumference must be greater than neck circumference for an accurate male calculation.'; return; } bodyFatPercentage = 86.010 * logWaistNeck – 70.041 * logHeight + 36.76; } else if (genderFemale) { // Women: Body Fat % = 163.205 * log10(waist + hip – neck) – 97.684 * log10(height) – 78.387 var logWaistHipNeck = Math.log10(waist + hip – neck); var logHeight = Math.log10(height); if (isNaN(logWaistHipNeck) || (waist + hip – neck) <= 0) { resultDiv.innerHTML = 'The sum of waist and hip circumference must be greater than neck circumference for an accurate female calculation.'; return; } bodyFatPercentage = 163.205 * logWaistHipNeck – 97.684 * logHeight – 78.387; } if (bodyFatPercentage < 0) { bodyFatPercentage = 0; // Body fat cannot be negative } resultDiv.innerHTML = '' + bodyFatPercentage.toFixed(2) + '%'; displayBodyFatCategory(bodyFatPercentage); } function displayBodyFatCategory(bfp) { var genderMale = document.getElementById('genderMale').checked; var category = "; if (genderMale) { if (bfp <= 5) category = 'Essential Fat'; else if (bfp <= 13) category = 'Athletes'; else if (bfp <= 17) category = 'Fitness'; else if (bfp <= 24) category = 'Acceptable'; else category = 'Obese'; } else { // Female if (bfp <= 13) category = 'Essential Fat'; else if (bfp <= 20) category = 'Athletes'; else if (bfp <= 24) category = 'Fitness'; else if (bfp <= 31) category = 'Acceptable'; else category = 'Obese'; } document.getElementById('fatPercentageResult').innerHTML += 'Category: ' + category + ''; }

Understanding Body Fat Percentage

Body fat percentage is a measure of the amount of fat your body holds relative to your total body weight. It includes essential fat (necessary for survival and healthy bodily function) and storage fat (accumulated fat). Unlike Body Mass Index (BMI), which only considers height and weight, body fat percentage provides a more direct insight into your body composition.

Why is Body Fat Percentage Important?

• Health Indicator: High body fat percentages are associated with increased risks of various health issues, including heart disease, type 2 diabetes, high blood pressure, and certain cancers.
• Fitness Assessment: For athletes and fitness enthusiasts, monitoring body fat percentage can help track progress, optimize training, and achieve performance goals.
• Beyond the Scale: Two people with the same weight and height can have vastly different body fat percentages due to differences in muscle mass. Body fat percentage offers a more nuanced view of body composition than weight alone.

Body Fat Percentage Categories (American Council on Exercise – ACE)

Category	Women (% Fat)	Men (% Fat)
Essential Fat	10-13%	2-5%
Athletes	14-20%	6-13%
Fitness	21-24%	14-17%
Acceptable	25-31%	18-24%
Obese	32%+	25%+

How to Use This Calculator

1. Select Your Gender: Choose 'Male' or 'Female'. Note that the formula for women requires an additional hip measurement.
2. Enter Measurements:
   • Height: Measure your height in inches.
   • Neck Circumference: Measure around your neck just below the larynx (Adam's apple). Keep the tape horizontal.
   • Waist Circumference:
     • Men: Measure horizontally around your abdomen at the level of your navel.
     • Women: Measure horizontally around your natural waist, at the narrowest part of your torso.
   • Hip Circumference (Women Only): Measure horizontally around the largest circumference of your hips.
   Ensure all measurements are taken accurately and consistently. It's best to take measurements on bare skin and exhale normally.
3. Click "Calculate Body Fat": The calculator will display your estimated body fat percentage and categorize it according to standard ranges.

Limitations of the Navy Body Fat Formula

While the U.S. Navy Body Fat Formula is widely used and generally considered more accurate than BMI for estimating body fat, it's important to understand its limitations:

• Estimation, Not Exact: All body fat calculators provide an estimate. The most accurate methods (like DEXA scans or hydrostatic weighing) require specialized equipment.
• Measurement Error: The accuracy of the result heavily depends on the precision of your measurements. Small errors can lead to significant differences in the calculated percentage.
• Individual Variation: Body shapes vary greatly. The formula might not be equally accurate for all body types, especially those with very unusual proportions.
• Not for Medical Diagnosis: This calculator is for informational purposes only and should not be used to diagnose or treat any medical condition. Consult with a healthcare professional for personalized advice.

Regularly tracking your body fat percentage, along with other health metrics, can help you monitor your fitness journey and make informed decisions about your health and lifestyle.