Body Fat Calculator: US Navy & BMI Methods
Free online body fat calculator and web app. Estimate your body fat percentage with the US Navy method and the BMI method, and see your category, fat mass and lean body mass. Install it on your phone like an app.
What is body fat percentage?
Body fat percentage is the share of your total weight that is fat. The rest is lean body mass: muscle, bone, organs and water. Knowing it gives a clearer picture of your health and progress than weight or BMI alone.
Methods used by this calculator
| Method | What it uses |
|---|---|
| US Navy method | Height, neck and waist (plus hips for women) |
| BMI method | BMI, age and sex: 1.20 x BMI + 0.23 x age - 10.8 x sex - 5.4 (sex = 1 for men, 0 for women) |
The main result is the US Navy estimate. The BMI method and the average of both are shown for comparison.
Body fat categories
| Category | Women | Men |
|---|---|---|
| Essential fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32% and above | 25% and above |
How to measure accurately
Use a soft tape, stand relaxed and measure in the morning before eating. Take each measurement two or three times and use the average. Measure at the same spots every time so you can track real changes.
Limits of body fat calculators
Tape-based estimates are not as precise as DEXA scans or other lab tests, and results can be off for very muscular or very lean people. Use the number as a guide and watch the trend rather than a single reading.
What to do next
Use your lean body mass to refine your BMR Calculator result with the Katch-McArdle formula, then plan your intake with the TDEE Calculator, Calorie Calculator and Macro Calculator. You can also check your BMI or browse all free tools.
Frequently asked questions
What is a healthy body fat percentage?
It depends on sex and fitness level. By the American Council on Exercise categories, about 14-24% for men and 21-31% for women covers the fitness to average range. Essential fat is roughly 2-5% for men and 10-13% for women.
How accurate is the US Navy body fat method?
It is an estimate based on body measurements and can differ from lab methods such as DEXA by several percentage points. It is still useful for tracking change over time if you measure the same way each time.
How do I measure my neck, waist and hips?
Use a soft tape. Measure the neck just below the larynx, the waist at the navel (men) or the narrowest point (women), and the hips at the widest point. Keep the tape snug but not tight, and measure in the morning.
What is the difference between body fat percentage and BMI?
BMI only compares weight and height, so it cannot tell muscle from fat. Body fat percentage estimates how much of your weight is fat, which makes it more informative for athletes and muscular people.
How can I lower my body fat?
Eat in a modest calorie deficit, keep protein high, do strength training and get enough sleep. Aim for slow, steady loss, and talk to a doctor or dietitian before major changes.
Why do women have a higher body fat percentage than men?
Women need more essential fat to support hormonal and reproductive functions, so healthy ranges for women are higher than for men.
Disclaimer: This calculator gives estimates for general information only and is not medical advice. Consult a doctor or registered dietitian before major diet changes.
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