Calculator Body Fat

Body Fat Percentage Calculator (US Navy Method)

Estimate your body fat percentage using the widely recognized US Navy Body Fat Calculator method. This method relies on specific body measurements to provide a quick and non-invasive estimate. All measurements should be in inches.

function toggleHipInput() { var gender = document.querySelector('input[name="gender"]:checked').value; var hipDiv = document.getElementById('hipInputGroup'); if (gender === 'female') { hipDiv.style.display = 'block'; } else { hipDiv.style.display = 'none'; document.getElementById('hipCircumference').value = "; // Clear value when hidden } } function calculateBodyFat() { var gender = document.querySelector('input[name="gender"]:checked').value; var height = parseFloat(document.getElementById('heightInches').value); var neck = parseFloat(document.getElementById('neckCircumference').value); var waist = parseFloat(document.getElementById('waistCircumference').value); var hip = parseFloat(document.getElementById('hipCircumference').value); var resultDiv = document.getElementById('bodyFatResult'); resultDiv.style.color = '#155724'; // Reset color for new calculation resultDiv.style.backgroundColor = '#e9f7ef'; // Reset background 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.'; resultDiv.style.color = '#721c24'; resultDiv.style.backgroundColor = '#f8d7da'; return; } var bodyFatPercentage; if (gender === 'male') { if (waist <= neck) { resultDiv.innerHTML = 'For men, waist circumference must be greater than neck circumference for a valid calculation.'; resultDiv.style.color = '#721c24'; resultDiv.style.backgroundColor = '#f8d7da'; return; } // US Navy Body Fat Formula for Men (in inches) // BF% = 86.010 * log10(waist – neck) – 70.041 * log10(height) + 36.76 bodyFatPercentage = 86.010 * Math.log10(waist – neck) – 70.041 * Math.log10(height) + 36.76; } else { // female if (isNaN(hip) || hip <= 0) { resultDiv.innerHTML = 'Please enter a valid positive number for Hip circumference for females.'; resultDiv.style.color = '#721c24'; resultDiv.style.backgroundColor = '#f8d7da'; return; } if ((waist + hip – neck) <= 0) { resultDiv.innerHTML = 'For women, (waist + hip – neck) must be positive for a valid calculation. Please check your measurements.'; resultDiv.style.color = '#721c24'; resultDiv.style.backgroundColor = '#f8d7da'; return; } // US Navy Body Fat Formula for Women (in inches) // BF% = 163.205 * log10(waist + hip – neck) – 97.684 * log10(height) – 78.387 bodyFatPercentage = 163.205 * Math.log10(waist + hip – neck) – 97.684 * Math.log10(height) – 78.387; } if (bodyFatPercentage 100) bodyFatPercentage = 100; // Body fat cannot exceed 100% resultDiv.innerHTML = 'Your estimated Body Fat Percentage: ' + bodyFatPercentage.toFixed(2) + '%'; } // Initialize hip input visibility on page load document.addEventListener('DOMContentLoaded', function() { toggleHipInput(); });

Understanding Body Fat Percentage

Body fat percentage is a measure of how much of your total body weight is made up of fat. It's a more accurate indicator of fitness and health than just body weight or Body Mass Index (BMI), as it distinguishes between fat mass and lean mass (muscle, bone, organs).

Why is Body Fat Percentage Important?

Having too much or too little body fat can impact your health. High body fat percentages are associated with increased risks of heart disease, diabetes, high blood pressure, and certain cancers. Conversely, extremely low body fat can also be detrimental, affecting hormone production, immune function, and overall energy levels.

Methods for Measuring Body Fat

There are several ways to estimate body fat, each with varying levels of accuracy and accessibility:

• Skinfold Calipers: Measures the thickness of subcutaneous fat at various sites. Requires skill for accuracy.
• Bioelectrical Impedance Analysis (BIA): Uses a small electrical current to estimate body composition. Can be affected by hydration levels.
• Hydrostatic Weighing (Underwater Weighing): Considered a gold standard, but is complex and not easily accessible.
• DEXA Scan (Dual-energy X-ray Absorptiometry): Highly accurate, provides detailed body composition, but involves radiation and is costly.
• US Navy Body Fat Calculator: A practical and widely used method that relies on simple body measurements. While not as precise as DEXA, it offers a good estimate for general tracking.

How to Use the US Navy Body Fat Calculator Accurately

This calculator uses the US Navy Body Fat formula, which requires specific measurements. For the most accurate results:

1. Height: Measure your height without shoes.
2. Neck Circumference: Measure just below the larynx (Adam's apple), keeping the tape parallel to the floor. Do not flex your neck.
3. Waist Circumference (Men): Measure horizontally at the navel (belly button).
4. Waist Circumference (Women): Measure horizontally at the narrowest part of your waist, usually above the navel.
5. Hip Circumference (Women Only): Measure horizontally at the largest circumference of the buttocks.

Ensure the tape measure is snug but not compressing the skin. Take measurements three times and use the average for better consistency. All measurements should be in inches.

Interpreting Your Results

Body fat percentage ranges vary by age and gender. Here are general guidelines:

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

These ranges are general guidelines and can vary based on individual factors. Consult a healthcare professional for personalized advice.

Disclaimer

This calculator provides an estimate based on the US Navy Body Fat formula. It is not a substitute for professional medical advice or more precise body composition analysis methods. Individual results may vary, and factors like body type, muscle mass, and measurement accuracy can influence the outcome. Always consult with a healthcare provider or certified fitness professional for health assessments and guidance.