Body Fat Calculator
Free body fat calculator using the U.S. Navy method. Enter height, neck, waist, and hip measurements to get body fat percentage, fat mass, and lean body mass. Supports metric and imperial units for men and women. 100% client-side.
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What is Body Fat Calculator?
The Body Fat Calculator estimates your body fat percentage using the U.S. Navy circumference method, the same formula used by the U.S. military, firefighters, and police for fitness screening. You enter your height, neck, waist, and (for women) hip measurements along with your weight, and it instantly returns your body fat percentage, fat mass, and lean body mass, plus a category based on American Council on Exercise guidelines. Unlike BMI, which only considers height and weight, the Navy method accounts for where your body stores fat, making it a more meaningful indicator of body composition for fitness and health tracking. Everything runs in your browser — free, private, and no signup.
Key Benefits
- More accurate than BMI because it distinguishes fat from muscle
- Separate, science-based formulas for men and women
- Shows fat mass and lean body mass, not just a percentage
- Works with metric or imperial units
- 100% client-side and private — nothing is uploaded
Common Use Cases
- •Tracking fat-loss or muscle-gain progress over weeks and months
- •Setting realistic nutrition and protein targets for a cut or bulk
- •Fitness assessments for military, police, and firefighter candidates
- •Comparing body composition to standard ACE fitness categories
- •Personal health checkups without a clinic visit
How to Use the Body Fat Calculator
- Select Your Gender and Units: Choose Male or Female (the formula differs) and pick Metric (cm, kg) or Imperial (in, lbs). Women also enter a hip measurement.
- Measure Your Circumferences: Using a tape measure, record your neck and waist (at the navel level). For women, also measure the hips at their widest point. Stand relaxed and do not pull the tape tight.
- Enter Height and Weight: Add your height and weight so the tool can compute fat mass and lean body mass alongside the percentage.
- Press Calculate: Click Calculate to see your body fat percentage, the category it falls in, and a breakdown of fat versus lean mass.
Key Features
- U.S. Navy method calculation for accurate body fat percentage
- Separate formulas and categories for men and women
- Metric (cm, kg) and imperial (in, lbs) unit support with automatic conversion
- Body fat category classification based on American Council on Exercise guidelines
- Fat mass and lean body mass breakdown plus a full category chart