Body fat percentage is the proportion of your total body mass that is fat tissue. This free calculator uses the U.S. Navy circumference method (Hodgdon & Beckett, 1984) — one of the most accessible and widely validated field methods, requiring only a tape measure.
All measurements in centimetres. Waist measured at the narrowest point; hip at the widest point (women); neck just below the larynx.
Body fat categories
Category
Men
Women
Essential Fat
2 – 5%
10 – 13%
Athletes
6 – 13%
14 – 20%
Fitness
14 – 17%
21 – 24%
Average / Acceptable
18 – 24%
25 – 31%
Obese
25%+
32%+
How to take accurate measurements
Waist: measure at the narrowest point (for men, usually at the navel level).
Neck: measure just below the larynx (Adam's apple), tape slightly sloping downward at the front.
Hip (women): measure at the widest part of the hips/buttocks.
Keep the tape parallel to the floor and snug but not compressing the skin.
Take 2–3 measurements and use the average for best accuracy.
Comparison of body fat measurement methods
Method
Accuracy
Equipment needed
U.S. Navy (this calculator)
±3–4%
Tape measure only
Skinfold calipers (3–7 site)
±3–4%
Calipers + trained tester
DEXA scan
±1–2%
Medical facility
Hydrostatic weighing
±1–2%
Specialised lab
BIA (body impedance scale)
±3–5%
Consumer scale
References
Hodgdon, J.A. & Beckett, M.B. (1984). "Prediction of percent body fat for U.S. Navy men and women from body circumferences and height" — Naval Health Research Center
"ACSM's Guidelines for Exercise Testing and Prescription"
"Body Composition Assessment in Nutrition Research and Practice" — Heymsfield et al.
Body fat percentage is the proportion of your total body weight that consists of fat mass. The remainder — muscle, bone, water, and organs — is called lean body mass (LBM). Unlike BMI, which only uses height and weight, body fat percentage directly quantifies how much of your body is fat, making it a far more meaningful health and fitness metric.
Body fat serves essential functions: insulating organs, regulating hormones (especially in women), storing energy, and absorbing vitamins A, D, E, and K. The minimum essential fat levels are approximately 2–5% for men and 10–13% for women — falling below these levels causes serious health consequences including hormonal disruption and organ damage.
The distribution of fat also matters. Visceral fat (around abdominal organs) is metabolically active and strongly associated with cardiovascular disease, type 2 diabetes, and inflammation. Subcutaneous fat (under the skin) is less harmful. A waist circumference above 40 inches (men) or 35 inches (women) suggests excess visceral fat regardless of overall body fat percentage.
How the Navy Body Fat Method Works
The US Navy circumference method estimates body fat using simple tape measurements: neck, waist (for men), and hips (women only). The formula uses the logarithmic relationship between these measurements to estimate the density of fat versus lean tissue.
For men: % Body Fat = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
For women: % Body Fat = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
Measurement tips for accuracy: Measure your waist at the narrowest point (for men: at the navel). Measure your neck just below the larynx (Adam's apple), sloping slightly downward. For women, measure hips at the widest point. Take each measurement 3 times and use the average. Hold the tape snug but don't compress the skin. Measure in the morning before eating or exercising.
Frequently Asked Questions
What is a healthy body fat percentage for men and women?
Per the American Council on Exercise: Men — athletes 6–13%, fitness 14–17%, acceptable 18–24%, obese 25%+. Women — athletes 14–20%, fitness 21–24%, acceptable 25–31%, obese 32%+. Women naturally carry 5–8% more essential fat than men for hormonal and reproductive function. Age also increases typical body fat — an acceptable range for a 50-year-old is higher than for a 25-year-old.
How do I lose body fat without losing muscle?
The three keys to fat loss while preserving muscle: (1) Moderate calorie deficit — 300–500 cal/day below TDEE. Larger deficits accelerate muscle loss. (2) High protein — 0.7–1.0g per pound of bodyweight daily. Protein is the primary nutrient signal to preserve muscle tissue during a deficit. (3) Resistance training — lift weights 3–4x per week. Even without progressive overload, maintaining training volume preserves muscle during a cut.
Can I build muscle and lose fat at the same time?
Yes, but primarily for beginners, people returning from a training break, or overweight individuals. This is called "body recomposition." It requires eating at or slightly below maintenance calories with high protein (1g/lb bodyweight) and consistent resistance training. Progress is slower than pure bulking or cutting phases but avoids the cycle of gaining and losing fat. After your first 1–2 years of training, simultaneous muscle gain and fat loss becomes very difficult and dedicated bulk/cut phases become more effective.
