Body Fat Calculator
Estimate your body fat percentage using the US Navy circumference method — based on height plus neck and waist (and hip for women) measurements.
US Navy method — measurements in inches
How to use the Body Fat Calculator
- Enter your inputs into the Body Fat Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The US Navy body fat formula
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
All measurements in inches. The Navy method was developed for military fitness screening and is reasonably accurate within ±3–4% for most adults. Less reliable for extreme body compositions.
Worked example
A man with 70" height, 34" waist, 15" neck: BF% = 86.010·log10(19) − 70.041·log10(70) + 36.76 ≈ 17.0%. A measurement of 36" waist and same other values raises body fat to about 21.0%.
Frequently asked questions
What is a healthy body fat percentage?
For men: 10–20% (essential 2–5%, athletes 6–13%, fit 14–17%, average 18–24%, obese 25%+). For women: 18–28% (essential 10–13%, athletes 14–20%, fit 21–24%, average 25–31%, obese 32%+).
How accurate is the Navy method?
Within ±3–4% body fat compared to DEXA scans for typical adults. Less accurate at the extremes (very lean or very obese) and for highly muscular individuals.
Is there a more accurate method?
DEXA scan, hydrostatic weighing and BodPod are research-grade and accurate within ±1–2%. Skinfold calipers are slightly more accurate than tape-measure methods but require practice.