Body Fat Calculator
Estimate body fat percentage using the U.S. Navy circumference method (neck, waist, plus hip for women). Includes lean mass, fat mass, and category classification.
How to Use
- Pick your sex (the formula differs).
- Enter your height in cm.
- Measure neck circumference at the narrowest point below the larynx.
- Measure waist at the navel for men, at the narrowest point for women.
- Women also enter hip circumference at the widest point.
- Read body fat percentage, lean mass, fat mass, and category.
Healthy ranges
Frequently Asked Questions
How accurate is the Navy circumference method?
Within roughly ±3–4% body fat for most people compared to DEXA scans (the gold standard). Less accurate at extremes — lean athletes and very obese individuals tend to be over- or under-estimated. The method was developed by the U.S. Navy in the 1980s for fitness assessments and is still used by the military, fitness apps, and health insurers because it's free, fast, and reasonably accurate.
What's a healthy body fat percentage?
<strong>Men:</strong> essential 2–5%, athletes 6–13%, fitness 14–17%, average 18–24%, obese 25%+. <strong>Women:</strong> essential 10–13%, athletes 14–20%, fitness 21–24%, average 25–31%, obese 32%+. Women have inherently higher body fat for hormonal and reproductive reasons.
Why is body fat better than BMI?
BMI doesn't distinguish muscle from fat — a muscular athlete and an obese person can have the same BMI. Body fat percentage measures what BMI is meant to be a proxy for: how much of your weight is fat tissue. Both have value: BMI for population-level screening, body fat for individual assessment.
How do I take measurements correctly?
Use a flexible cloth tape measure. Don't pull tight — the tape should sit against the skin without compressing. Take measurements in the morning before eating or drinking. Measure 2–3 times and use the average. Have someone else measure if you can; self-measurement of the waist tends to underestimate.
How does this compare to skinfold or DEXA?
Skinfold (3- or 7-site) is more accurate (~±2%) but requires calipers and practice. Bioimpedance scales are convenient but vary widely with hydration. DEXA is the gold standard (~±1%) but expensive and requires a clinic visit. The Navy method is the best balance of accuracy and accessibility for at-home tracking.
Can I lose body fat without losing weight?
Yes — body recomposition. Strength training plus adequate protein at a slight deficit or maintenance can build muscle while losing fat, leaving the scale roughly unchanged but body composition meaningfully different. This is most pronounced in beginners and those returning from a layoff; advanced athletes find it harder.
Common Use Cases
Tracking fitness progress
Body fat percentage shows recomposition progress that the scale alone can't reveal — losing fat while building muscle keeps weight stable but reduces body fat.
Athletic performance benchmarks
Sport-specific body fat targets: distance runners 6–12% (men) / 14–20% (women); bodybuilders sub-10% in competition; team-sport athletes 10–15%.
Health screening
Insurance, military, and law enforcement often use body fat in lieu of BMI for fitness eligibility.
Weight-loss goal setting
Set targets by body fat percentage rather than weight to focus on the right metric.
Recovery from injury
After detraining, track body composition to understand how much weight regain is muscle vs. fat.
Pre/post-program assessment
Measure before and after a 12-week training block to quantify body-composition change.
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