Body Percentage Calculator

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Body Fat Percentage Calculator

Estimate your body composition using the U.S. Navy Method

Male Female
–%
Category: —

What is Body Fat Percentage?

Body fat percentage (BFP) is the total mass of fat divided by total body mass, multiplied by 100. Unlike Body Mass Index (BMI), which only considers height and weight, body fat percentage distinguishes between muscle mass and fat mass. This makes it a far more accurate indicator of physical fitness and health risks.

How This Calculator Works

This tool uses the U.S. Navy Fitness Equation, a widely recognized method for estimating body composition without expensive equipment like DXA scans or hydrostatic weighing. It relies on specific circumference measurements which correlate strongly with internal fat deposits.

Body Fat Categories

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

Realistic Example Calculations

Example 1 (Male): A man who is 180 cm tall, weighs 85 kg, with a 40 cm neck and 92 cm waist.
Result: Approximately 20.4% (Average category).

Example 2 (Female): A woman who is 165 cm tall, weighs 65 kg, with a 34 cm neck, 75 cm waist, and 95 cm hips.
Result: Approximately 24.8% (Fitness category).

Tips for Accurate Measurement

  • Neck: Measure below the larynx, sloping slightly downward to the front.
  • Waist: For men, measure at the navel. For women, measure at the narrowest point of the natural waistline.
  • Hips (Women only): Measure at the widest horizontal circumference of the buttocks.
  • Consistency: Measure in the morning before eating and try to be consistent with tape placement.
function toggleHipField() { var gender = document.getElementById('gender').value; var hipGroup = document.getElementById('hip-group'); if (gender === 'female') { hipGroup.style.display = 'flex'; } else { hipGroup.style.display = 'none'; } } function calculateBFP() { var gender = document.getElementById('gender').value; var weight = parseFloat(document.getElementById('weight').value); 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); var resultDiv = document.getElementById('bfp-result'); var resVal = document.getElementById('res-val'); var resCat = document.getElementById('res-cat'); var resMass = document.getElementById('res-mass'); if (!weight || !height || !neck || !waist || (gender === 'female' && !hip)) { alert('Please enter all required measurements.'); return; } var bfp = 0; if (gender === 'male') { // US Navy Formula for Men (using Metric) // 495 / (1.0324 – 0.19077 * log10(waist – neck) + 0.15456 * log10(height)) – 450 bfp = 495 / (1.0324 – 0.19077 * (Math.log10(waist – neck)) + 0.15456 * (Math.log10(height))) – 450; } else { // US Navy Formula for Women (using Metric) // 495 / (1.29579 – 0.35004 * log10(waist + hip – neck) + 0.22100 * log10(height)) – 450 bfp = 495 / (1.29579 – 0.35004 * (Math.log10(waist + hip – neck)) + 0.22100 * (Math.log10(height))) – 450; } if (isNaN(bfp) || bfp <= 0) { alert('Please check your measurements. The calculation resulted in an invalid number.'); return; } var leanMass = weight * (1 – (bfp / 100)); var category = ""; if (gender === 'male') { if (bfp < 6) category = "Essential Fat"; else if (bfp < 14) category = "Athlete"; else if (bfp < 18) category = "Fitness"; else if (bfp < 25) category = "Average"; else category = "Obese"; } else { if (bfp < 14) category = "Essential Fat"; else if (bfp < 21) category = "Athlete"; else if (bfp < 25) category = "Fitness"; else if (bfp < 32) category = "Average"; else category = "Obese"; } resVal.innerHTML = bfp.toFixed(1) + "% Body Fat"; resCat.innerHTML = "Category: " + category; resMass.innerHTML = "Estimated Lean Body Mass: " + leanMass.toFixed(1) + " kg"; resultDiv.style.display = 'block'; resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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