This calculator estimates your body fat percentage using the U.S. Navy circumference method — a tape-measure formula built from your height, neck, and waist measurements (plus hips for women). Enter your numbers below to get an instant estimate and see which body fat category you fall into.
The American Council on Exercise (ACE) splits body fat percentage into five categories, defined separately for men and women. Ranges are shown in percent body fat.
| Category | Body Fat % |
|---|---|
| Essential Fat | 10–13% |
| Athletes | 14–20% |
| Fitness | 21–24% |
| Average | 25–31% |
| Obese | 32%+ |
| Category | Body Fat % |
|---|---|
| Essential Fat | 2–5% |
| Athletes | 6–13% |
| Fitness | 14–17% |
| Average | 18–24% |
| Obese | 25%+ |
The U.S. Navy method estimates body fat percentage from a small set of body circumference measurements instead of skinfold calipers, underwater weighing, or a DEXA scan. It was developed by researchers Hodgdon and Beckett at the Naval Health Research Center as a fast, low-cost way to assess body composition for military fitness standards, and it has since become one of the most widely used at-home body fat formulas.
Men need three measurements: height, neck circumference, and waist circumference (measured at the navel). Women need a fourth measurement, hip circumference at its widest point, because the formula accounts for how body fat is distributed differently between sexes.
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
All measurements are in inches. This calculator converts metric entries to inches automatically before applying the formula, then displays your result as a percentage.
For most people, the Navy method is accurate to within about 3–4 percentage points of more precise lab methods like DEXA or hydrostatic weighing. It tends to be less reliable for people with atypical fat distribution, including very muscular or very lean individuals. Because it's fast and equipment-free, it's best used to track your own trend over weeks and months rather than as a one-time clinical measurement.
Body Mass Index (BMI) is calculated only from height and weight, so it cannot tell the difference between fat mass and muscle mass. Body fat percentage instead measures the actual proportion of your body composed of fat, which makes it a more direct read on body composition. A muscular athlete can have a BMI in the "overweight" range while still having a low, healthy body fat percentage, and two people with an identical BMI can have very different body fat percentages depending on how much muscle each one carries.
For men, a healthy range is generally 14-17% (Fitness) to 18-24% (Average). For women, a healthy range is generally 21-24% (Fitness) to 25-31% (Average). Essential fat, 2-5% for men and 10-13% for women, is the minimum your body needs for basic physiological function, not a target. These ranges follow the American Council on Exercise (ACE) body fat classification.
The Navy tape-measurement method is generally accurate to within about 3-4 percentage points of more precise lab methods like DEXA scans or hydrostatic weighing for most body types. Accuracy drops for people with unusual fat distribution, such as very muscular or very lean individuals. It works best for tracking trends over time rather than as a single precise clinical measurement.
BMI is calculated only from height and weight, so it cannot distinguish fat mass from muscle mass. Body fat percentage measures the actual proportion of your body made up of fat, giving a more direct picture of body composition. Two people can share the same BMI and have very different body fat percentages depending on how much muscle they carry.
You only need a flexible tape measure. Men need three measurements — height, neck, and waist — while women also need a hip measurement. No calipers, scales, or lab equipment are required for the Navy method. Measure each circumference snugly without compressing the skin, and take readings at the same spot each time for consistency.
Most people get the most useful data by re-measuring every 2-4 weeks, since body composition changes slowly and single readings can be skewed by water retention or recent meals. Measuring at the same time of day, such as first thing in the morning, improves consistency. Track the trend across months rather than reacting to any one number.
Men and women store and distribute body fat differently, and women naturally carry more essential fat to support reproductive function. The Navy method accounts for this by adding a hip measurement for women and using formula coefficients calibrated separately for each sex. Using the formula for the correct sex is necessary for an accurate estimate.
This calculator is provided for informational and educational purposes only and is not a substitute for professional medical or clinical assessment. It does not diagnose, treat, or provide personalized health advice. For a more accurate body composition measurement, consider a DEXA scan, hydrostatic (underwater) weighing, or air displacement plethysmography (Bod Pod), all of which are more precise than tape-measurement estimates. Speak with a doctor or qualified healthcare provider before starting a new diet, exercise, or weight-management program, particularly if you have an existing health condition.