How to use this calculator
Select your gender and enter your height, weight, and circumference measurements with a soft tape measure. Measure your neck just below the larynx, your waist at the navel (relaxed, not sucked in), and — for women — your hips at the widest point. Hit calculate to see your body fat percentage, fat mass, lean mass, and category.
What is the U.S. Navy method?
The U.S. Navy circumference method estimates body fat percentage from a few simple tape measurements. It was developed at the Naval Health Research Center and is still used by the U.S. military for body composition screening, because it requires no special equipment and tracks change over time reliably.
It is not as precise as a DEXA scan, but for tracking trends — is your body fat going up or down — it is one of the most practical tools available.
How is body fat calculated?
The Navy formulas
Men:
BF% = 86.010 × log(waist − neck) − 70.041 × log(height) + 36.76
Women:
BF% = 163.205 × log(waist + hip − neck) − 97.684 × log(height) − 78.387
// Then:
Fat mass = weight × BF% ÷ 100
Lean mass = weight − fat mass
Formula source: Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, Reports 84-29 & 84-11, 1984.
Body fat categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Categories from the American Council on Exercise (ACE) body fat classification.
Tips for accurate measurements
- Measure first thing in the morning, before eating or drinking
- Keep the tape level and snug against the skin — but never compressing it
- Stand relaxed — don't flex or suck in your waist
- Take each measurement two or three times and use the average
- Re-measure under the same conditions each time to track trends reliably
Why body fat beats scale weight
Two people of identical height and weight can look and perform completely differently depending on how much of that weight is muscle versus fat. Tracking body fat percentage tells you whether a weight change is fat loss or muscle loss — the scale alone cannot. Combined with a TDEE-based calorie target, it is the foundation of effective recomposition.
Frequently asked questions
Studies show the Navy method is typically within 3 to 4 percentage points of DEXA scan results for most people. Its real strength is consistency: measured the same way each time, it tracks changes in body fat reliably, which matters more than absolute precision for most fitness goals.
For men, 14 to 17% is considered fit and 18 to 24% average; for women, 21 to 24% is fit and 25 to 31% average. Athletes typically range 6 to 13% (men) and 14 to 20% (women). Going below essential fat levels — 2 to 5% for men, 10 to 13% for women — is dangerous.
Women store proportionally more fat in the hips and thighs, while men store it predominantly around the waist. Adding the hip circumference lets the formula capture that distribution and produces a significantly more accurate estimate for women.
At the navel, standing relaxed, at the end of a normal exhale. Don't pull the tape tight enough to compress the skin and don't suck in — both will understate your true measurement and your body fat result.
Yes — body recomposition is most achievable for newer lifters, people returning after a layoff, and those with higher starting body fat. It requires adequate protein (around 0.7 to 1 g per pound of body weight), progressive strength training, and a small or zero calorie deficit.
Every 2 to 4 weeks is plenty. Day-to-day water shifts can move tape measurements by a quarter inch or more, which swamps real fat changes. Always measure under the same conditions — same time of day, same tape tension.
Important
Not medical advice. The Navy method is an estimate based on population averages and can be less accurate for very muscular, very lean, or very tall individuals. It is intended for healthy adults tracking fitness trends. For clinical body composition assessment, ask your healthcare provider about DEXA or similar methods.