Body Fat Calculator

Estimate your body fat percentage using the US Navy method or BMI-based formula.

Weight (kg)

Height (cm)

Neck circumference (cm)

Waist circumference (cm)

Fill in all fields to see your body fat percentage.

How to Use

Select sex and method

Choose Navy method (more accurate) or BMI method (simpler).

Enter weight and height

Use accurate measurements in centimetres and kilograms.

Measure circumferences (Navy method)

Measure neck, waist, and hips (females) at the correct anatomical points.

Review body fat category

See your percentage and ACE category from Essential Fat to Obese.

Understanding Body Fat Percentage

Body fat percentage is a more precise health indicator than BMI because it distinguishes fat mass from lean mass (muscle, bone, organs, water). Two people with identical weights and heights can have very different body compositions — and very different health profiles.

Real-World Examples & Use Cases

Beyond BMI for Athletes

Athletes often have 'overweight' BMIs due to high muscle mass. Body fat percentage correctly identifies them as lean and fit. A 85 kg athlete at 180 cm has a BMI of 26.2 (overweight) but may have only 10% body fat (athletic category) — making body fat percentage far more informative.

Fitness Progress Tracking

During a body recomposition program (building muscle while losing fat), scale weight may stay constant while body fat decreases. Tracking body fat percentage monthly reveals progress invisible to the scale, providing motivation and data even when weight doesn't change.

Health Risk Assessment

Excess visceral fat (abdominal fat) is linked to cardiovascular disease and type 2 diabetes independent of total weight. The Navy method's waist measurement captures abdominal fat distribution, making it a useful proxy for metabolic risk beyond simple weight measurements.

Military and Athletic Selection Criteria

Military branches and athletic organizations use body fat percentage standards for fitness assessment. US Army, Navy, and Air Force each have maximum body fat limits by age and sex. Athletes in weight-class sports (boxing, wrestling) monitor body fat to optimize power-to-weight ratio.

How It Works

US Navy Method: Male: BF% = 495 / (1.0324 - 0.19077×log₁₀(waist - neck) + 0.15456×log₁₀(height)) - 450 Female: BF% = 495 / (1.29579 - 0.35004×log₁₀(waist + hip - neck) + 0.22100×log₁₀(height)) - 450 All measurements in centimetres. BMI Method (Deurenberg): BF% = (1.20 × BMI) + (0.23 × age) - (10.8 × sex) - 5.4 sex: male=1, female=0 ACE Body Fat Categories (Male/Female): Essential fat: 2–5% / 10–13% Athletes: 6–13% / 14–20% Fitness: 14–17% / 21–24% Acceptable: 18–24% / 25–31% Obese: 25%+ / 32%+

Frequently Asked Questions

What is the most accurate way to measure body fat?▼

DEXA (dual-energy X-ray absorptiometry) scan is the gold standard, providing full-body fat, muscle, and bone density maps with ~1-2% accuracy. Hydrostatic weighing (water displacement) and Bod Pod (air displacement) are also highly accurate. Bioelectrical impedance (smart scales) has 3-8% error depending on hydration. The Navy circumference method used here has about 3-4% margin of error — much better than smart scales in many conditions.

What body fat percentage is considered healthy?▼

ACE healthy ranges: Men: 14–17% (fitness) to 18–24% (acceptable). Women: 21–24% (fitness) to 25–31% (acceptable). Athletes are leaner: 6–13% men, 14–20% women. Below essential fat levels (under 5% men, under 10% women) is dangerous to health. Essential fat is required for organ protection, hormonal function, and neurological health.

How do I measure neck circumference correctly for the Navy method?▼

Measure your neck just below the larynx (Adam's apple) with the tape perpendicular to the neck's long axis. Keep your head level. Measure waist at the navel (not the narrowest point). Measure hips (females) at the widest point of the buttocks. Use a flexible measuring tape and take measurements in the morning before eating for consistency.

Can body fat percentage be too low?▼

Yes. Below essential fat levels (approximately 5% for men, 10-13% for women), health complications arise: hormonal disruption, immune suppression, bone density loss, and organ damage. Female athletes below 17% may experience the Female Athlete Triad (low energy availability, menstrual dysfunction, low bone density). Extreme leanness seen in competitive bodybuilding is not considered healthy year-round.

Why is the same body fat percentage in different locations so different in risk?▼

Visceral fat (stored around organs in the abdomen) is metabolically active and releases inflammatory compounds directly into portal circulation, raising cardiovascular and metabolic disease risk. Subcutaneous fat (stored under skin at hips, thighs) is metabolically less active and less risky. Two people with identical total body fat percentages can have very different health risks depending on fat distribution — waist-to-hip ratio and waist circumference provide additional risk information beyond total body fat percentage.

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