Calculate Body Composition

Body Composition Calculator

Use this calculator to estimate your body fat percentage, fat mass, and lean body mass using the U.S. Navy Body Fat Formula.

Select Gender Male Female

document.getElementById('gender').onchange = function() { var gender = document.getElementById('gender').value; if (gender === 'female') { document.getElementById('hipCircumferenceGroup').style.display = 'block'; } else { document.getElementById('hipCircumferenceGroup').style.display = 'none'; document.getElementById('hipCircumference').value = "; // Clear hip value if gender changes } }; function log10(val) { return Math.log(val) / Math.log(10); } function calculateBodyComposition() { var gender = document.getElementById('gender').value; var heightInches = parseFloat(document.getElementById('heightInches').value); var weightPounds = parseFloat(document.getElementById('weightPounds').value); var neckCircumference = parseFloat(document.getElementById('neckCircumference').value); var waistCircumference = parseFloat(document.getElementById('waistCircumference').value); var hipCircumference = parseFloat(document.getElementById('hipCircumference').value); var resultDiv = document.getElementById('bodyCompositionResult'); resultDiv.innerHTML = "; // Clear previous results if (!gender) { resultDiv.innerHTML = 'Please select your gender.'; return; } if (isNaN(heightInches) || heightInches <= 0) { resultDiv.innerHTML = 'Please enter a valid height in inches.'; return; } if (isNaN(weightPounds) || weightPounds <= 0) { resultDiv.innerHTML = 'Please enter a valid weight in pounds.'; return; } if (isNaN(neckCircumference) || neckCircumference <= 0) { resultDiv.innerHTML = 'Please enter a valid neck circumference.'; return; } if (isNaN(waistCircumference) || waistCircumference <= 0) { resultDiv.innerHTML = 'Please enter a valid waist circumference.'; return; } if (gender === 'female' && (isNaN(hipCircumference) || hipCircumference <= 0)) { resultDiv.innerHTML = 'Please enter a valid hip circumference for females.'; return; } var bodyFatPercentage; if (gender === 'male') { if (waistCircumference <= neckCircumference) { resultDiv.innerHTML = 'For males, waist circumference must be greater than neck circumference for accurate calculation.'; return; } bodyFatPercentage = 86.010 * log10(waistCircumference – neckCircumference) – 70.041 * log10(heightInches) + 36.76; } else { // female if ((waistCircumference + hipCircumference – neckCircumference) <= 0) { resultDiv.innerHTML = 'For females, (waist + hip – neck) must be a positive value for accurate calculation. Please check your measurements.'; return; } bodyFatPercentage = 163.205 * log10(waistCircumference + hipCircumference – neckCircumference) – 97.684 * log10(heightInches) – 78.387; } if (bodyFatPercentage 100) bodyFatPercentage = 100; // Body fat cannot exceed 100% var fatMassPounds = weightPounds * (bodyFatPercentage / 100); var leanBodyMassPounds = weightPounds – fatMassPounds; resultDiv.innerHTML = '

Your Body Composition Estimates:

' + 'Body Fat Percentage: ' + bodyFatPercentage.toFixed(2) + '%' + 'Fat Mass: ' + fatMassPounds.toFixed(2) + ' lbs' + 'Lean Body Mass: ' + leanBodyMassPounds.toFixed(2) + ' lbs'; }

Understanding Your Body Composition

Body composition refers to the proportion of fat and non-fat mass in your body. A healthy body composition is crucial for overall health, fitness, and disease prevention. It's a more accurate indicator of health than just body weight, as two people of the same weight and height can have vastly different body compositions.

What is Body Composition?

Your body is made up of two main types of mass: fat mass and fat-free mass (also known as lean body mass). Fat mass includes all the fat in your body, both essential fat (necessary for basic bodily functions) and storage fat. Lean body mass includes muscles, bones, organs, and water.

• Body Fat Percentage: This is the percentage of your total body weight that is fat. It's a key metric for assessing health risks.
• Fat Mass: The total weight of fat in your body, typically measured in pounds or kilograms.
• Lean Body Mass: The total weight of everything in your body that isn't fat, including muscle, bone, and water.

Why is Body Composition Important?

Maintaining a healthy body fat percentage is linked to a lower risk of chronic diseases such as heart disease, type 2 diabetes, high blood pressure, and certain cancers. A higher lean body mass is often associated with a higher metabolism, greater strength, and better physical performance.

How is Body Composition Measured?

There are various methods to measure body composition, ranging from simple to highly accurate:

• Skinfold Calipers: Measures the thickness of subcutaneous fat at various sites.
• Bioelectrical Impedance Analysis (BIA): Sends a small electrical current through the body to estimate body fat based on resistance.
• Hydrostatic Weighing (Underwater Weighing): Considered a gold standard, it measures body density by submerging a person in water.
• DEXA Scan (Dual-Energy X-ray Absorptiometry): Another highly accurate method that uses X-rays to differentiate between bone, fat, and lean mass.
• Circumference Measurements (U.S. Navy Method): This method, used in the calculator above, uses specific body measurements (height, neck, waist, hip) to estimate body fat percentage. While less precise than DEXA or hydrostatic weighing, it's a convenient and non-invasive option for a reasonable estimate.

Interpreting Your Results (U.S. Navy Method)

The U.S. Navy method provides an estimate. Here are general guidelines for body fat percentages, though ideal ranges can vary based on age, activity level, and individual goals:

For Men:

• Essential Fat: 2-5%
• Athletes: 6-13%
• Fitness: 14-17%
• Acceptable: 18-24%
• Obese: 25% and above

For Women:

• Essential Fat: 10-13%
• Athletes: 14-20%
• Fitness: 21-24%
• Acceptable: 25-31%
• Obese: 32% and above

Remember, these are general guidelines. Consult with a healthcare professional or certified fitness expert for personalized advice and interpretation of your results.

Example Calculation:

Let's consider an example for a male:

• Gender: Male
• Height: 70 inches
• Weight: 180 pounds
• Neck Circumference: 15.5 inches
• Waist Circumference: 34 inches

Using the formula for men:

Body Fat % = 86.010 * log10(34 - 15.5) - 70.041 * log10(70) + 36.76

Body Fat % = 86.010 * log10(18.5) - 70.041 * log10(70) + 36.76

Body Fat % = 86.010 * 1.267 - 70.041 * 1.845 + 36.76

Body Fat % = 108.99 - 129.22 + 36.76

Body Fat % = 16.53%

Based on this, the fat mass would be 180 lbs * (16.53 / 100) = 29.75 lbs, and lean body mass would be 180 lbs - 29.75 lbs = 150.25 lbs.

This result of 16.53% falls within the "Fitness" category for men, indicating a healthy body fat level.