Body Fat Calculator
Body fat percentage is a more accurate health marker than BMI because it distinguishes between fat mass and lean mass (muscle, bone, water). A muscular 200 lb person and a sedentary 200 lb person can have the same BMI but wildly different health profiles. Our body fat calculator uses the US Navy method (neck, waist and hip measurements — no calipers needed) which is accurate to within 2–3 percentage points for most people.
Body Fat
About the Body Fat Calculator
Body fat percentage is a more accurate health marker than BMI because it distinguishes between fat mass and lean mass (muscle, bone, water). A muscular 200 lb person and a sedentary 200 lb person can have the same BMI but wildly different health profiles. Our body fat calculator uses the US Navy method (neck, waist and hip measurements — no calipers needed) which is accurate to within 2–3 percentage points for most people.
How to use it
- Select your gender.
- Enter your height, and measurements for waist (at the navel), neck and — for women — hips.
- Read your estimated body fat percentage and fat mass vs lean mass in pounds/kg.
- Check the fitness category your result falls in.
Formula & methodology
US Navy Method (men): %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Women: %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387.
Common use cases
- Tracking body composition changes during a cut or bulk
- Setting a realistic body fat goal (e.g. 15% to see ab definition)
- Comparing progress beyond the scale (weight might stay flat while body fat drops)
- Determining if a BMI "overweight" result is actually muscle mass
- Setting military or sports fitness targets
Frequently asked questions
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