Body fat percentage calculator
Estimate body fat percentage using the US Navy circumference method. Shows fat mass, lean mass and fitness classification.
- Free, no sign-up
- No data stored
- Reviewed 2026-01-15
Your details
Results
- Fat mass
- 39.5 lb
- Lean mass
- 35.5 lb
- BMI method
- 3.6 %
- Bmi
- 1.7
- Ffmi
- 0.8
Bmi method note
Ffmi note
- Fat category essential
- Fat category athlete
- Fat category fitness
- Fat category average
- Fat category obese
Body fat note
About the Body Fat Calculator
Estimate your body fat percentage using tape measurements (neck, waist, hip for women) with the US Navy circumference formula. The result is classified against ACE fitness categories.
Body fat percentage gives a clearer picture of health than BMI alone, distinguishing between fat and lean tissue.
How to use the Body Fat Calculator
- Select metric or imperial units.
- Enter height, weight, age and sex.
- Measure neck and waist circumference.
- Women: also measure hip circumference.
- View body fat %, fat mass, lean mass and category.
Frequently asked questions
How accurate is the Navy method?
Within ±3–4% of hydrostatic weighing for most people. It is less accurate for very lean or very obese individuals.
What body fat is healthy?
For men: 10–20% is fitness range, 18–25% is acceptable. For women: 18–28% is fitness range, 25–32% is acceptable. Below essential fat (men <3%, women <12%) is dangerous.
Where do I measure waist circumference?
Measure at the narrowest point of your torso, typically at navel level, standing relaxed. Use a non-elastic tape directly on skin.
Sources
Figures are estimates for guidance only. Always confirm with the official source or a qualified professional before acting on them.