Calculated using standard mathematical and industry formulas.
Your body fat percentage represents the proportion of adipose tissue relative to total body weight. Calculated using the scientifically validated US Navy tape measure method (neck, waist, and hip circumferences), it distinguishes healthy lean muscle mass from fat storage far more accurately than BMI. Ideal body fat ranges are 10–20% for men and 18–28% for women.
How to use this calculator?
Select your unit system (metric or imperial) and biological sex.
Enter your age, height, and body weight.
Measure your neck circumference just below the larynx (adam's apple).
Measure your waist circumference horizontally at the navel level for men or narrowest point for women.
For women, measure hip circumference at the widest point.
Read your body fat percentage, fat mass, lean mass, and ACE body fat category.
Measurements in cm. Fat Mass = Weight × (BF% ÷ 100). Lean Mass = Weight − Fat Mass.
Step-by-step calculation example
Male 175cm height, 75kg weight, 38cm neck, 85cm waist → Body Fat ≈ 18.2% (Average range, 13.6 kg fat mass, 61.4 kg lean mass).
Key insights to remember
The US Navy body fat method estimates body composition within 3–4% accuracy compared to DEXA scans.
Body fat percentage is a better indicator of fitness and health risks than BMI alone because it distinguishes muscle from fat.
Essential body fat is approximately 2–5% for men and 10–13% for women, necessary for nerve function and hormone regulation.
Fat mass can be reduced through a calorie deficit and cardiovascular exercise, while resistance training preserves lean body mass.
Fluctuations in body water content can cause minor day-to-day changes in tape measurements; measure consistently under similar conditions.
How to interpret your results?
Essential Fat vs. Storage Fat Categories
American Council on Exercise (ACE) standards: Essential Fat (Men: 2–5%, Women: 10–13%), Athletes (Men: 6–13%, Women: 14–20%), Fitness (Men: 14–17%, Women: 21–24%), Average (Men: 18–24%, Women: 25–31%), and Obese (Men: 25%+, Women: 32%+).
Why BMI is Outdated for Athletic Bodies
BMI relies solely on height and weight, misclassifying muscular lifters as overweight. Body fat calculation isolates actual lean tissue from adipose fat.
Expert advice & guidance
💡 Body recomposition tip: Focus on waist-to-hip measurements and body fat trends rather than bathroom scale weight. Gaining 3 lbs of dense muscle while losing 3 lbs of bulky fat leaves scale weight unchanged while transforming physical waist size and metabolic health.
Frequently asked questions
How to measure waist and hips correctly for body fat calculation?
To measure waist accurately: wrap a flexible tape measure around your torso at the level of your navel (belly button) horizontally, relaxed at the end of a normal exhale without sucking in your stomach. For hips (women), measure around the widest circumference of your buttocks.
Does muscle weigh more than fat and is muscle denser than fat?
One pound of muscle weighs exactly the same as one pound of fat (16 ounces), but muscle is roughly 18% denser than fat. A five-pound block of fat takes up noticeably more physical volume than five pounds of compact, firm muscle tissue, drastically altering appearance.
How to build muscle mass and lose fat at the same time (body recomposition)?
Body recomposition (losing fat while gaining muscle) requires progressive resistance training 3 to 5 times per week, maintaining a high protein intake of 1.6 to 2.2 grams per kilogram of body weight, and sustaining a slight caloric deficit or maintenance intake (±200 to 300 kcal).
How to check body fat percentage and how accurate is the US Navy method?
The US Navy circumference method is one of the most reliable field tests, typically exhibiting a margin of error of only 3% to 4% compared to gold-standard DEXA scans. For highest accuracy, measure circumferences in the morning before breakfast with consistent tape tension.
Is BMI outdated compared to body fat percentage?
Yes, BMI is increasingly considered outdated for active individuals because it fails to distinguish between fat mass, lean muscle, and bone density. Body fat percentage directly quantifies metabolic health risk and physical fitness by measuring actual fat tissue ratio.
Related calculators
BMI Calculator: Body Mass Index for Adults — Calculate your Body Mass Index (BMI) using metric or imperial units. Compare your score with official WHO weight categories from underweight to obese.
Calorie Calculator: Daily Maintenance & Loss — Calculate daily calories for weight loss, maintenance, or muscle gain. Uses Mifflin-St Jeor and Harris-Benedict formulas to set safe, healthy calorie targets.