Body Fat % Estimator
Estimate your body fat percentage using the U.S. Navy method — just a tape measure and your height. No gym equipment needed.
Measure at the narrowest point (around the navel for men, smallest point for women)
Measure just below the larynx (Adam's apple)
Measure at the widest point of your hips/buttocks
| Essential fat | 2–5% |
| Athletes | 6–13% |
| Fitness | 14–17% |
| Average | 18–24% |
| Obese | 25%+ |
How is body fat % calculated?
This calculator uses the U.S. Navy circumference method, developed for fitness assessment in the armed forces. It estimates body fat from simple body measurements rather than requiring expensive equipment.
The formula
Men: %BF = 495 / (1.0324 − 0.19077 × log10(waist − neck) + 0.15456 × log10(height)) − 450
Women: %BF = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
Accuracy
The Navy method has a margin of error of approximately ±3–4%. It's a useful tracker for progress over time, but for precise body composition assessment, DEXA scan or hydrostatic weighing are more accurate.
Body fat percentage categories
Body composition classification systems typically break body fat percentage into five bands, based on health and performance research:
| Category | 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%+ |
Essential fat is the minimum needed for basic physiological function — hormone production, organ protection, and cell structure — and should not be pursued as a long-term target. The "athletes" and "fitness" bands are sustainable ranges for people who train seriously, while "average" reflects typical population figures for generally healthy adults.
Other ways to measure body fat
The tape-measure method used here is the most accessible option, but several alternatives exist with different tradeoffs between cost, convenience, and accuracy:
- Skinfold calipers: ±3–4% accuracy in trained hands; cheap but technique-dependent and less reliable when self-administered.
- Bioelectrical impedance (smart scales): ±4–6% accuracy; convenient but sensitive to hydration status, meaning results can swing several percentage points day to day.
- DEXA scan: ±1–2% accuracy, the clinical gold standard; also shows fat distribution and bone density, but requires a specialist facility and costs money per scan.
- Hydrostatic (underwater) weighing: ±1–2% accuracy; historically the research standard, now largely replaced by DEXA due to being more accessible.
- Bod Pod (air displacement): ±2–3% accuracy; fast and comfortable, available at some sports science labs and gyms.
For most people tracking progress over time, consistency matters more than precision — using the same method, at the same time of day, under similar conditions (e.g. always in the morning before eating) gives a more useful trend than switching between methods.