Body Fat Calculator

Estimate your body fat percentage using the US Navy Method. Enter your measurements to see your body fat %, fitness category, lean body mass, and fat mass.

FAQ

What is the US Navy Method for body fat?
The US Navy Method estimates body fat percentage using circumference measurements at the neck, waist, and hips (for women). Developed by the US Navy, it's a simple and reliable alternative to calipers and body fat scales.
How accurate is the Navy Method?
Studies show the US Navy Method is typically accurate within 3-4% of more advanced methods like DEXA scans. Accuracy depends on consistent measuring technique, so measure at the same spot each time.
How do I measure my waist and neck?
Measure your neck just below the larynx (Adam's apple) while looking straight ahead. Measure your waist at the navel (belly button) after a normal exhale. For hips (women), measure at the widest point of the buttocks.
What is a healthy body fat percentage?
For men, 10-20% is generally healthy. For women, 18-28% is healthy. Athletes typically carry less (men 6-13%, women 14-20%), while essential fat minimums are 2-5% for men and 10-13% for women.
Is body fat percentage better than BMI?
Body fat percentage distinguishes between muscle and fat, making it more accurate for athletes and muscular individuals. However, BMI is still useful for general population screening and is quicker to calculate.
How accurate is the US Navy body fat method?
The US Navy circumference method is accurate within ±3–4% compared to gold-standard methods like underwater weighing or DEXA scans. It's most accurate for average-built individuals. Very muscular people may see higher estimates because the formula doesn't distinguish muscle from fat in the waist measurement. For clinical accuracy, a DEXA scan is the best option.
Where exactly should I measure my neck and waist?
Neck: measure just below the larynx (Adam's apple) with the tape horizontal and flat against the skin. Waist (men): at the level of the navel, tape horizontal, abdomen relaxed (do not pull in your stomach). Waist (women): at the natural narrowest point. Hips (women): at the widest point of the buttocks. Measure against bare skin for best results.
What body fat percentage is considered healthy?
For men, 10–20% is generally healthy, with 6–13% being athletic. For women, 18–28% is healthy, with 14–20% being athletic. Women naturally need more body fat for reproductive health. Essential fat minimums are 2–5% for men and 10–13% for women — going below these levels is medically dangerous.
Is body fat percentage better than BMI?
For most people, yes. BMI only considers height and weight, treating all weight equally. Two people with identical BMI can have vastly different body fat percentages — a muscular athlete and a sedentary person may both have a BMI of 27, but very different health profiles. Body fat percentage gives a much clearer picture of metabolic health and fitness.

How to Use the Body Fat Calculator

  1. Enter your measurements — height, neck circumference, and waist circumference. For women, also enter hip circumference. Use a flexible tape measure for accuracy.
  2. Select your gender — the US Navy formula uses different equations for men and women.
  3. Choose your unit system — metric (cm) or imperial (inches). The calculator handles conversion automatically.
  4. Click "Calculate" to see your body fat percentage, fitness category, lean body mass, and fat mass.
  5. Track over time — measure under consistent conditions (same time of day, same measuring technique) for reliable comparisons.

Understanding Body Fat Percentage and the US Navy Method

Body fat percentage is a more meaningful health indicator than BMI because it distinguishes between fat mass and lean mass (muscle, bone, organs, water). The US Navy method used by this calculator estimates body fat from circumference measurements. For men: %BF = 495 ÷ (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450. For women, hip circumference is added to the equation. The method was developed by the US Navy for fitness assessments and is widely used due to its simplicity and reasonable accuracy (±3–4% compared to underwater weighing).

Healthy body fat ranges differ by gender and age. For men, 10–20% is generally considered healthy, with 6–13% being athletic and 25%+ classified as obese. For women, 18–28% is healthy (women naturally carry more essential fat), with 14–20% being athletic and 32%+ classified as obese. Essential fat — the minimum needed for survival — is about 2–5% for men and 10–13% for women. Going below these levels is dangerous and can impair hormone production, immune function, and cognitive performance.

For accurate Navy method measurements, follow proper technique. Measure the neck just below the larynx (Adam's apple) with the tape perpendicular to the long axis of the neck. For men, measure the waist at the navel level, keeping the tape horizontal and relaxed (don't suck in). For women, measure the waist at the narrowest point and the hips at the widest point. Take measurements in the morning before eating, and have someone else help for consistency. The Navy method tends to overestimate body fat for very lean, muscular individuals and underestimate for those with central obesity.

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