How does the US Navy body fat method work?

The US Navy method uses circumference measurements: for men, neck and waist; for women, neck, waist and hips. It uses logarithmic formulas to estimate body fat percentage with reasonable accuracy without equipment.

How accurate is body fat percentage calculated from measurements?

The US Navy method is accurate to within 3-4% compared to DEXA scans. It is one of the most accurate non-equipment methods. For best accuracy, take measurements in the morning before eating and measure 3 times, using the average.

How do I measure my waist for body fat calculation?

Measure your waist at the narrowest point — about 1 inch above the navel for men, or at the belly button. Stand relaxed, breathe normally, and measure at the end of a normal exhale. Do not suck in your stomach.

💪 Fitness Calculator

Body Fat Calculator

Calculate your body fat percentage using the US Navy method, BMI method or skinfold estimates. Get fat mass, lean mass and your fitness category.

Select gender

Units:

Basic measurements

Age (years)

Height (cm)

Weight (kg)

Neck circumference (cm)

Measure below larynx, slightly downward slope

Circumference measurements

Waist (cm)

Men: at navel level · Women: narrowest point

Body fat percentage --% --

--Fat mass

--Lean mass

--BMI

Where you fall on the scale --%

EssentialAthleteFitnessAverageObese

Body fat categories — Men

Category	Body fat %	Status

💡 Personalised tips

⚠️ This calculator estimates body fat using mathematical formulas. Results may vary ±3–5% from clinical methods (DEXA scan). For health decisions, consult a doctor or certified fitness professional.

How is body fat percentage calculated?

This calculator uses two validated methods. The US Navy method uses body circumference measurements and is accurate to within 3–4% of DEXA scans. The BMI method estimates body fat from height, weight and age, which is less precise but requires no measurements.

🇺🇸 US Navy Method

Uses neck, waist (and hips for women) circumferences with a logarithmic formula. It is the official method used by the US military. More accurate than BMI-based estimates.

📊 BMI Method

Estimates body fat from BMI, age and gender. Uses the Deurenberg formula. Less accurate because BMI doesn't distinguish between fat and muscle mass.

📏 Taking measurements

Use a flexible measuring tape. Measure morning before eating. Take 3 readings and use the average. Tape should be snug but not compressing skin. Stand relaxed, breathe normally.

🎯 Goal body fat

For health: Men 15–20%, Women 22–28%. For athletic performance: Men 6–13%, Women 14–20%. For general fitness: Men 14–17%, Women 21–24%.

Frequently asked questions

What is a healthy body fat percentage?

Men: Essential fat 2–5%, Athletes 6–13%, Fitness 14–17%, Average 18–24%, Obese 25%+. Women: Essential fat 10–13%, Athletes 14–20%, Fitness 21–24%, Average 25–31%, Obese 32%+. These are general guidelines — ideal body fat depends on age and individual health conditions.

How accurate is the US Navy body fat method?

The US Navy method has a margin of error of approximately 3–4% compared to DEXA (dual-energy X-ray absorptiometry) scans, which are the clinical gold standard. It is more accurate than BMI-based estimates, especially for muscular individuals. For best accuracy, measure 3 times and use the average.

How do I reduce body fat percentage?

Sustainable fat loss requires a calorie deficit (200–500 calories/day below maintenance), adequate protein intake (1.6–2.2g per kg of body weight), resistance training to preserve muscle mass, and cardiovascular exercise. Losing 0.5–1% body fat per month is a realistic and sustainable rate.

Why is essential fat necessary?

Essential fat (2–5% for men, 10–13% for women) is required for basic physiological functions including organ protection, hormone regulation, and nerve function. Going below essential fat levels is dangerous and associated with serious health complications.

Is BMI or body fat percentage more accurate?

Body fat percentage is far more informative than BMI. BMI cannot distinguish fat from muscle — a very muscular person may have a high BMI but low body fat. Body fat percentage directly measures the ratio of fat to total body mass, giving a much more accurate picture of health and fitness.