Body Fat Percentage Calculator
Estimate your body fat percentage using the U.S. Navy circumference method — accurate within 3% of DEXA scan results for most adults.
How to use this body fat calculator
- 1Measure waist at the narrowest point (navel level) with relaxed, natural posture — do not suck in.
- 2Measure neck just below the Adam's apple, keeping the tape horizontal.
- 3Women: measure hips at the widest point around the buttocks.
- 4Take each measurement 2–3 times and use the average for best accuracy.
- 5Use the same flexible fabric tape and same time of day each session for consistent tracking.
How it's calculated
Men: 86.010×log10(waist−neck) − 70.041×log10(height) + 36.76. Women: 163.205×log10(waist+hip−neck) − 97.684×log10(height) − 78.387.
About the Body Fat Calculator
Body fat percentage is arguably the most important single metric for body composition, yet it remains less commonly tracked than body weight despite being far more informative. The scale tells you how heavy you are; body fat percentage tells you what you are made of.
Tracking body fat percentage over time is more valuable than any single reading. A person beginning a strength training and fat loss program might see scale weight change minimally over three months while body fat percentage drops from 28% to 22% — a dramatic improvement invisible on the scale because muscle gain offsets fat loss. This is why combining body fat tracking with body weight measurement gives a complete picture that either measurement alone cannot provide.
For health risk assessment, body fat distribution matters as much as total body fat percentage. Visceral fat — surrounding internal organs in the abdominal cavity — is metabolically active and strongly associated with insulin resistance, type 2 diabetes, cardiovascular disease, and systemic inflammation, even at normal total body fat percentages. The Navy circumference method approximates visceral fat indirectly through waist measurement — a large waist relative to height and neck suggests excess visceral fat regardless of total percentage.
For most people, the practical path to improved body fat percentage is not complicated: create a modest calorie deficit, maintain or increase protein intake, do resistance training 2–4 times per week, sleep 7–9 hours per night, and repeat consistently for 3–6 months. Individual variation in the rate of change is real, but the direction of change from this combination is nearly universal.
Frequently asked questions
How accurate is the Navy body fat method?
The Navy circumference method has been validated against gold-standard methods in multiple studies. For the general population, it has a standard error of approximately 3–4 percentage points — meaning it typically estimates within 3–4% of true body fat. It is less accurate at very low body fat (below 10% for men) and very high levels (above 35%). Despite this, it is substantially more informative than BMI because it estimates fat mass rather than total weight relative to height. For tracking changes over time with the same technique, it is quite reliable and more accessible than any other method.
What is a healthy body fat percentage?
Healthy ranges differ between men and women due to hormonal and reproductive needs. For men: essential fat is 2–5%, athletes carry 6–13%, fitness category is 14–17%, average is 18–24%, and obese is 25%+. For women: essential fat is 10–13%, athletes carry 14–20%, fitness is 21–24%, average is 25–31%, and obese is 32%+. These ranges are guidelines. Athletic ranges are associated with optimal physical performance, while average ranges are associated with reasonable health outcomes. Most health-focused individuals should target the fitness category rather than athlete levels unless actively training at high volume.
What is the most accurate way to measure body fat?
DEXA (Dual-Energy X-ray Absorptiometry) scanning is the gold standard for body composition assessment — it measures bone density, lean mass, and fat mass separately with high precision and can differentiate regional fat distribution. Hydrostatic (underwater) weighing is also highly accurate. In practical settings, 7-site skinfold caliper testing by a trained technician is accurate to within 2–3%. The Navy method achieves similar accuracy without equipment or technical training. Consumer bioelectrical impedance scales are less reliable and heavily influenced by hydration status.
How can I reduce body fat percentage most effectively?
The most effective evidence-based approach combines: (1) Moderate calorie deficit (300–500 below TDEE) — aggressive deficits increase muscle loss. (2) High protein intake (0.7–1.0 g per pound of body weight) — protein is the primary driver of muscle preservation during fat loss. (3) Resistance training — preserves and builds muscle mass, maintains metabolic rate. (4) Adequate sleep (7–9 hours) — poor sleep elevates cortisol and ghrelin, increasing fat storage and appetite. (5) Consistency over months, not weeks. This combination produces fat loss with muscle preservation, improving body fat percentage faster than cardio-only approaches.
Does body fat percentage matter more than weight?
For health and fitness outcomes, body composition is more meaningful than total weight. Two people weighing 180 lbs may have dramatically different health profiles: one at 15% body fat (27 lbs fat, 153 lbs lean) and another at 30% body fat (54 lbs fat, 126 lbs lean). The first has twice the muscle mass and substantially lower metabolic risk. Scale weight matters because excess fat is associated with health risks, but the fat-to-muscle ratio matters more than the number on the scale. This is why strength training — which builds muscle while potentially slowing scale weight loss — is so valuable for health.