Body Fat Percentage Calculator
U.S. Navy circumference method — the most accurate field measurement technique.
Shows body fat %, lean mass, fat mass, and health category.
Navy method · ±3–4% accuracy · Health categories · BMI comparison
Body Fat % Calculator (U.S. Navy Method)
Units:
How to measure: Neck — just below the larynx (Adam's apple), horizontal. Waist — at the narrowest point, horizontal. Hips (women) — at the widest point around the buttocks.
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Body Fat % Categories — Men & Women
| Category | Men | Women | What it means |
|---|---|---|---|
| Essential Fat | 2–5% | 10–13% | Minimum fat for basic physiological functions |
| Athlete | 6–13% | 14–20% | Lean, highly trained; competitive athletes |
| Fitness | 14–17% | 21–24% | Good fitness; active lifestyle |
| Acceptable | 18–24% | 25–31% | Average; below this threshold is healthy |
| Obese | 25%+ | 32%+ | Above healthy range; increased health risk |
Source: American Council on Exercise (ACE). These are general guidelines — consult a physician for personal health assessment.
U.S. Navy Body Fat Formula
The Navy method was developed for military fitness assessments and remains one of the most validated field methods. It uses neck and waist circumference (plus hips for women) with height to estimate fat percentage without expensive equipment.
Formulas (measurements in inches)
Men: Body Fat % = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
Women: Body Fat % = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Accuracy vs other methods
- DEXA scan: Gold standard, ±1–2% accuracy
- Navy method: ±3–4% accuracy, widely accessible
- Skinfold calipers: ±3–5% with experienced tester
- Bioelectrical impedance (scale): ±5–8%, highly affected by hydration
- BMI-derived: ±5–10%, cannot account for muscle mass
FAQ
Body fat calculator questions
How accurate is the Navy body fat method?
The U.S. Navy method is typically within 3–4% of DEXA scan results, which is considered clinically acceptable. Accuracy depends on correct measurement technique — especially measuring at the right locations. Consistent re-testing (same time of day, same measurer) is more important than absolute accuracy for tracking progress.
What is a healthy body fat percentage?
Men: 14–24% is the "fitness to acceptable" range. Women: 21–31%. Athletic ranges are lower: 6–13% men, 14–20% women. Essential fat minimums are 2–5% for men and 10–13% for women — going below these is dangerous. Optimal health ranges vary by age.
How do I measure waist and neck correctly?
Neck: just below the larynx (Adam's apple), horizontal. Don't tilt head. Waist (men): at the narrowest point, usually at or just above the navel, horizontal. Waist (women): at the narrowest point of the torso. Hips (women): at the widest point of the buttocks. Breathe normally — don't suck in.
What is the difference between BMI and body fat percentage?
BMI = weight ÷ height². It cannot distinguish muscle from fat. A muscular 200-lb man might be "overweight" by BMI but have only 12% body fat. Body fat percentage directly measures what fraction of your weight is fat — it's a much better indicator of health and fitness than BMI.