Body Fat Percentage Calculator
This calculator uses the U.S. Navy circumference method — the same approach used in military fitness assessments — to estimate body fat percentage from your height and a few circumference measurements, no scale required.
How the Body Fat Percentage formula works
The Navy method (measurements in centimeters, base-10 logarithm):
Men: BF% = 495 / (1.0324 − 0.19077×log10(waist − neck) + 0.15456×log10(height)) − 450 Women: BF% = 495 / (1.29579 − 0.35004×log10(waist + hip − neck) + 0.22100×log10(height)) − 450
Step-by-step calculation
- Measure neck, waist (and hip, for women) circumference and height in centimeters.
- Take the base-10 logarithm of the relevant circumference combination.
- Plug the values into the sex-specific Navy formula.
- The result is an estimated body fat percentage.
Worked example
A man who is 180 cm tall with a 90 cm waist and 38 cm neck: log10(90−38) = log10(52) ≈ 1.716. log10(180) ≈ 2.255. BF% = 495 / (1.0324 − 0.19077×1.716 + 0.15456×2.255) − 450 ≈ 18.7%.
Frequently asked questions
How accurate is the Navy method compared to other methods?
It's typically within 3–4% of more precise methods like DEXA scans for most body types, which makes it a reasonable at-home estimate, though it can be less accurate for people with atypical fat distribution or very high muscle mass.
Where exactly should I measure my waist and neck?
Measure the neck just below the larynx, and the waist at its narrowest point (or at the navel, per the standard Navy protocol) — measuring at inconsistent points is the most common source of error.
What's a healthy body fat percentage range?
Commonly cited healthy ranges are roughly 10–20% for men and 18–28% for women, though the ideal range varies with age, athletic goals, and individual health context.