Body Fat Calculator
Estimate your body fat percentage using the US Navy method (Hodgdon-Beckett). Enter height, neck, waist (and hip for women). Shows the fitness category. Everything in your browser.
Gordura corporal estimada
0%
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Estimativa. Para diagnóstico nutricional preciso, consulte profissional de saúde.
Verifique as medidas — a cintura deve ser maior que o pescoço.
Como medir corretamente
- Pescoço: abaixo do pomo de Adão, com a fita reta.
- Cintura/abdômen: homens medem na altura do umbigo; mulheres no ponto mais estreito.
- Quadril (apenas mulheres): no ponto mais largo dos glúteos.
- Altura: sem sapatos, costas eretas contra a parede.
A fórmula da Marinha dos EUA (Hodgdon-Beckett) usa essas medidas para estimar a densidade corporal e converter em percentual de gordura via equação de Siri. Margem de erro típica: ±3%. Tudo é calculado no navegador.
Body fat percentage: formulas and methods
Body fat percentage estimates the share of body mass that is adipose tissue. The U.S. Navy method (Hodgdon-Beckett) uses tape measurements: for men, %BF = 86.010·log10(waist − neck) − 70.041·log10(height) + 36.76; for women, %BF = 163.205·log10(waist + hip − neck) − 97.684·log10(height) − 78.387 (measurements in inches; the tool converts cm). Jackson-Pollock uses 3 skinfolds with a caliper: men measure chest, abdomen, thigh; women measure triceps, suprailiac, thigh. The gold standard is DEXA scan (±2% precision), followed by Bod Pod and hydrostatic weighing. Bioimpedance scales vary with hydration. Example: man with 175 cm height, 85 cm waist, 38 cm neck — Navy formula yields ≈18% body fat.
Practical ranges and clinical context
ACE body fat ranges — men: essential 2–5%, athletes 6–13%, fitness 14–17%, acceptable 18–24%, obesity ≥25%. Women: essential 10–13%, athletes 14–20%, fitness 21–24%, acceptable 25–31%, obesity ≥32%. Women carry more essential fat for hormonal and reproductive function. Limitations: sex, age, pregnancy, ascites, and very muscular or very obese body shapes can shift estimates. Body fat % is more informative than BMI for athletes but should be combined with waist circumference and clinical evaluation.
FAQ
How accurate is the Navy formula? Typical error is ±3–4% versus DEXA. Good enough to track trends; not a diagnostic.
Why are women's essential fat levels higher? Sex-specific fat in breasts, hips, and reproductive tissues is needed for hormone production and fertility.
Is bioimpedance better than tape measurements? Not necessarily — household scales fluctuate up to ±5% with hydration, recent meals, and exercise.
What's the most accurate method? DEXA scan (radiological), then Bod Pod (air displacement) and hydrostatic weighing. All require a clinic.
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Estimate your body fat percentage
The number on the scale doesn't separate muscle from fat, and that's why body fat percentage tells you far more about body composition. This calculator estimates that percentage with the US Navy method (Hodgdon-Beckett), which needs only tape-measure measurements.
You enter height, neck and waist circumference (for women, the hip too) and the tool works out the percentage along with the matching fitness category. It's an accessible alternative for following your progress over time, without relying on lab equipment.
Worth remembering that this is an estimate: to assess body composition precisely, clinical methods and a professional's guidance remain the ideal. Everything is calculated in the browser, with none of your measurements stored.