Navy Body Fat Calculator
Estimate your body fat percentage with the U.S. Navy circumference method, which needs only a tape measure. Add your age and weight to also see your fat mass, lean body mass, an age-based ideal target, the fat you would shed to reach it, and whether you meet the Navy body-composition standard. Men enter height, neck, and waist; women add a hip measurement.
Formula
Worked example
A man 180 cm tall with a 90 cm waist and 38 cm neck: 495 ÷ (1.0324 − 0.19077·log₁₀(52) + 0.15456·log₁₀(180)) − 450 ≈ 19.8% body fat. At 80 kg that is about 15.8 kg of fat and 64.2 kg of lean mass.
How the U.S. Navy method works
The U.S. Navy circumference method estimates body fat from tape measurements rather than a scale, calipers, or a lab scan. It was developed by Navy researchers (Hodgdon and Beckett) in the 1980s and uses base-10 logarithms of your circumferences and height to predict the percentage of your body weight that is fat. Men supply height, neck, and waist; women add a hip measurement because fat distributes differently between the sexes. Because it needs only a flexible tape, it is the assessment the military uses in the field and a practical at-home screen.
Fat mass, lean mass, and your ideal target
Add your weight and the calculator turns the percentage into real mass. Body fat mass is simply your body fat percent times your weight, and lean body mass is whatever is left, the muscle, bone, organs, and water that the fat sits around. Tracking lean mass alongside fat is useful during a cut, since the goal is usually to drop fat while holding lean tissue. The tool also shows a Jackson and Pollock ideal body fat percentage for your age, then estimates the fat you would need to lose to reach it while keeping your lean mass constant. Ideal ranges rise gently with age because some increase in body fat is normal as we get older.
The Navy standard and how to interpret your number
The military standard is a pass/fail limit rather than a fitness ideal, and it differs from the general reference ranges. The Navy applies two numbers. The pass/fail maximum, set by the Department of Defense and used in the Navy body composition assessment, is 26 percent for men and 36 percent for women at every age. Alongside it the Navy publishes graduated standards by age (men 22 percent up to age 21, 23 percent at 22 to 29, 24 percent at 30 to 39 and 26 percent at 40 and over; women 33, 34, 35 and 36 percent across the same bands), and a sailor above the graduated figure is enrolled in the fitness enhancement program even though the assessment is still a pass. This calculator shows the graduated standard for your age and sex, and the insight compares you with the pass/fail maximum too. Branches update their instructions and methods periodically, so always confirm against your branch current policy. Treat every number here as an estimate, not a diagnosis. Studies put the Navy method within roughly three to four percentage points of a DEXA scan for most people, but it can be off further for very lean, very muscular, or larger individuals. Re-measure under the same conditions every few weeks and watch the direction of travel.
Measuring accurately
Accuracy depends almost entirely on careful measurement, since the formula is sensitive to a centimeter or two. Use a non-stretch tape and keep it level and snug without compressing the skin. Measure your neck just below the larynx, your waist at the navel for men or at the narrowest point for women, and, for women, your hips at their widest. Measure on bare skin after a normal exhale, take each reading two or three times, and average them. Consistent technique matters more than any single perfect measurement, especially when tracking change over time.
Body-fat categories and age-based ideal (ACE, Jackson & Pollock)
| Category / age | Women | Men |
|---|---|---|
| Essential fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Above average | 32%+ | 25%+ |
| Ideal at age 20 | 17.7% | 8.5% |
| Ideal at age 30 | 19.3% | 12.7% |
| Ideal at age 40 | 22.2% | 15.3% |
| Ideal at age 50 | 25.2% | 18.9% |
American Council on Exercise body-fat bands plus the Jackson & Pollock ideal target by age. Healthy ranges differ by sex and rise gently with age; the Navy fitness standard is a separate, age-banded ceiling.
Frequently asked questions
How accurate is the Navy body fat calculator?
It is a screening estimate. Validation studies generally place it within about three to four percentage points of a DEXA scan for typical adults, but it can be less accurate for very muscular, very lean, or larger people. Careful, consistent tape measurement is the biggest factor in getting a reliable number.
How do I get fat mass and lean body mass?
Enter your weight in the optional weight field. The calculator multiplies your body fat percentage by your weight to get fat mass, then subtracts that from your weight to get lean body mass. It also estimates how much fat you would need to lose to reach the age-based ideal target while holding your lean mass steady.
Why do women need a hip measurement but men do not?
Women carry more body fat around the hips and thighs, so the Navy formula for women includes the hip circumference to capture that distribution. The men’s formula relies on the difference between waist and neck. Using the wrong formula for your sex will give a misleading result.
Is this the same as the official military body fat standard?
It uses the same circumference method the U.S. military applies. The Navy body composition assessment fails a sailor only above the Department of Defense maximum of 26 percent for men and 36 percent for women, while the Navy graduated standards by age shown here (22 to 26 percent for men, 33 to 36 percent for women) decide who is enrolled in the fitness enhancement program. Limits vary by branch and policies are updated periodically, so consult your branch current instruction for the official assessment.