Body Fat Calculator

The Body Fat Calculator estimates your body fat percentage using body measurements. Unlike BMI, body fat percentage distinguishes between fat mass and lean mass (muscle, bone, organs), providing a more accurate picture of body composition and health.

Body fat is essential for normal body functions — it cushions organs, insulates the body, stores energy, and produces hormones. However, excess body fat increases health risks. Essential fat is 2–5% for men and 10–13% for women. Athletes typically carry 6–13% (men) or 14–20% (women), while a healthy range for the general population is 14–24% (men) or 21–31% (women).

How the Formula Works

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.

How to Use This Calculator

  1. Select your sex
  2. Enter your height, waist, neck, and hip (women) circumferences
  3. Click Calculate to see your estimated body fat percentage
  4. Review the body fat category chart

Tips & Best Practices

  • Measure circumferences at the same time of day for consistency
  • Body fat percentage is more meaningful than weight — you can gain muscle and lose fat at the same weight
  • Women naturally carry more essential fat than men for reproductive health
  • Losing 1% body fat is approximately equivalent to losing 1.5–2 lbs of pure fat (depending on body weight)

Important Limitations

  • The Navy method is an estimate — actual body fat can differ by 3–4%
  • Measurement accuracy depends on consistent tape placement
  • Not as accurate for very lean or very obese individuals
  • Does not indicate where fat is distributed (visceral vs. subcutaneous)
HomeFitness & HealthBlogUnit Converters