Body Fat Percentage Calculator – Estimate Your Body Fat

Calculate your body fat percentage using the U.S. Navy method. Enter your measurements and get an accurate estimate of body fat, lean mass, and fitness category.

What is body fat percentage?

Body fat percentage is the proportion of your total body weight that is stored fat. It's a far more meaningful metric than weight alone because two people at the same weight can have vastly different body compositions. A 180-pound person at 15% body fat looks and performs very differently from a 180-pound person at 30% body fat.

How the U.S. Navy method works

The U.S. Navy body fat formula estimates body fat percentage using simple tape measurements. It was developed by the Naval Health Research Center and has been validated against hydrostatic weighing. The formula uses:

  • For men: Height, waist circumference, and neck circumference. BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
  • For women: Height, waist, hip, and neck circumference. BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387

The formula is accurate to within 1–3% of DEXA scans for most people. It's widely used by the U.S. military, sports teams, and fitness professionals because it requires no special equipment — just a measuring tape.

How to take accurate measurements

Proper measurement technique is critical for accurate results:

  • Neck: Measure just below the larynx (Adam's apple), perpendicular to the long axis of the neck. Keep the tape snug but not tight. Round up to nearest 0.5 cm.
  • Waist (men): Measure at the navel level, standing upright, after exhaling normally. Round up to nearest 0.5 cm.
  • Waist (women): Measure at the narrowest point of the waist (natural waistline). Round up to nearest 0.5 cm.
  • Hip (women only): Measure at the widest point of the buttocks/hips, feet together. Round down to nearest 0.5 cm.
  • Height: Stand barefoot against a wall, look straight ahead. Measure from floor to top of head.

For the most consistent results, measure first thing in the morning before eating or drinking, and take each measurement twice, using the average.

Body fat categories explained

Body fat percentage is categorized differently for men and women due to differences in essential fat requirements:

  • Essential fat: 2–5% men / 10–13% women. Minimum for survival and hormonal function. Going below this is dangerous and unsustainable.
  • Athletes: 6–13% men / 14–20% women. Typical of competitive athletes, bodybuilders (off-season), and fitness models. Requires dedicated training and strict nutrition.
  • Fitness: 14–17% men / 21–24% women. Lean and healthy appearance. Achievable with regular exercise and a balanced diet.
  • Average: 18–24% men / 25–31% women. Typical for adults with moderate activity. Generally considered healthy but room for improvement.
  • Obese: 25%+ men / 32%+ women. Associated with increased risk of cardiovascular disease, type 2 diabetes, and other health conditions.

Body fat percentage vs. BMI

BMI (Body Mass Index) only uses height and weight — it can't distinguish between muscle and fat. A muscular athlete might have a "overweight" BMI of 28 but a healthy body fat of 12%. Conversely, someone with low muscle mass ("skinny fat") might have a normal BMI but an elevated body fat percentage. That's why this calculator shows both metrics so you can see the full picture.

How to reduce body fat percentage

Lowering body fat while preserving muscle requires a strategic approach:

  • Moderate calorie deficit: Aim for 300–500 calories below maintenance. Aggressive deficits increase muscle loss.
  • High protein intake: 1.6–2.2 g per kg of body weight to preserve lean mass during the deficit.
  • Resistance training: Lifting weights signals your body to keep muscle. Without it, up to 25% of weight lost can be muscle.
  • Sufficient sleep: Poor sleep increases cortisol and ghrelin, promoting fat storage and cravings.
  • Patience: Healthy fat loss is 0.5–1.0% body fat per month. Faster rates typically sacrifice muscle.

Comparing body fat measurement methods

No method is perfect. Here's how common methods compare:

  • DEXA scan: Gold standard. ±1–2% accuracy. Costs $50–150 per scan.
  • U.S. Navy tape method: ±1–3% accuracy. Free. Consistent when done correctly.
  • Bioelectrical impedance (BIA): ±3–5% accuracy. Affected by hydration status. Found in smart scales.
  • Skinfold calipers: ±3–4% accuracy. Depends heavily on the technician's skill.
  • Visual estimation: ±5%+ accuracy. Useful as a rough guide but unreliable for tracking.

How this calculator works

This calculator uses the U.S. Navy circumference method — the same formula used by the U.S. Department of Defense. It estimates body fat from height, neck, waist (and hip for women) measurements. Results include body fat %, fat mass, lean mass, BMI, and a color-coded fitness category.

Bottom line

Body fat percentage gives you a much clearer picture of your health than weight alone:

  • It reveals the quality of your weight — fat vs. lean tissue
  • It's a better predictor of health risks than BMI
  • Tracking it over time shows real progress beyond the scale
  • Measure consistently (same time, same technique) for reliable trends

Use this calculator to find your starting point, then let AI Meal Planner create a nutrition plan tailored to your body composition goals.

Get Your Personalized Meal Plan

Nutrition plan based on your body composition. Free to start.

Frequently Asked Questions

The U.S. Navy method is accurate to within 1–3% of more advanced methods like DEXA scans for most people. It works best when measurements are taken consistently at the same time of day. It may be less accurate for very lean or very overweight individuals.

Healthy ranges vary by gender. For men, 10–20% is generally considered healthy, with athletes often at 6–13%. For women, 18–28% is healthy, with athletes at 14–20%. Essential fat (the minimum needed for normal function) is about 2–5% for men and 10–13% for women.

The U.S. Navy formula uses the ratio of neck, waist, and (for women) hip circumference to height to estimate body fat. Fat tends to accumulate around the waist, while a thicker neck relative to waist indicates more muscle mass. These proportions correlate well with actual body fat percentage.

BMI only uses height and weight, so it can't distinguish between muscle and fat. A muscular person may have a high BMI but low body fat. Body fat percentage directly estimates how much of your weight is fat vs lean mass, giving a more accurate picture of body composition.

Every 2–4 weeks is ideal. Body fat changes slowly, so daily measurements will mostly show noise from hydration and measurement variation. Always measure at the same time of day (morning is best) and use the same technique for consistent tracking.