Body Fat US Navy Calculator

Use the Body Fat US Navy Calculator to estimate your body fat percentage based on your gender, height, and waist and neck size (plus hips for women). 

This tool uses the tape-measure equations known as the US Navy formula to estimate your body fat and your fat to lean tissue ratio. It gives you a body fat estimate. The Navy’s own test has worked differently since 2026: it starts with your waist-to-height ratio and no longer measures your neck. The US Navy Body Fat Standards section below covers the current limits and the two-step test. 

What is The Body Fat US Navy Calculator?

As the name suggests, this tool is based on the US Navy formula. It estimates your body fat percentage from your sex, height, waist and neck (plus hips for women). Your weight then turns that percentage into pounds or kilograms of fat mass and lean mass. 

The formula comes from the military: recruits, including those joining the Navy, have to meet body composition standards to enlist, and the Navy used this formula to check them.

How To Use The Body Fat US Navy Calculator

While the calculator is rather straightforward to use, it’s important to ensure you provide accurate information to get the best result possible. 

The best time to weigh yourself and take your waist and neck measurements is first thing upon waking after you’ve used the bathroom and before eating or drinking anything. 

Step 1: Leave the method on US Navy (tape measure) and choose your units: US (pounds, feet and inches) or Metric (kilograms and centimeters). 

Step 2: Choose the gender

Step 3: Enter your current weight, height and age (the calculator is for adults, 18 and over)

Step 4: Enter your waist: across the navel (belly button) for men, and at the narrowest point for women, about halfway between the navel and the bottom of the breastbone. 

Step 5: Enter neck measurement (Narrowest part of the neck below the larynx)

Step 6: Enter hip measurement at the widest (only for Female)

Step 7: Hit Calculate body fat!

Analyzing Your Results

The calculator will display estimates of your body fat percentage, fat mass in pounds/kg, lean mass in pounds/kg, the method’s typical error, and your body fat category on the American Council on Exercise (ACE) chart.

So, for example, if you’re a 30-year-old, 5’10 male who weighs 142 lbs and has a 32-inch waist and 14-inch neck, your results will look like the following. 

• Body fat: 15.5%
• Fat mass: 22.0 lb
• Lean mass: 120.0 lb
• ACE category: Fitness
• Typical error: ±3.5 points (a lab test would usually land within about 12.0% to 19.0%)

So based on your results, you have 15.5% body fat, 22.0 pounds of fat mass, 120.0 pounds of lean mass (muscles, bone, organs, etc), and you’re in ACE’s Fitness range. The category ranges are in the Body Fat Categories Table below. 

How To Take Waist, Neck and Hip Measurements

While this part should not be difficult, many times it’s frustrating trying to get an accurate measurement. 

Waist

Men measure the waist across the navel, also known as the belly button. Women measure the natural waist, the narrowest point, about halfway between the navel and the bottom of the breastbone; if you can’t find it, measure at a few heights there and use the smallest number. If you are a woman and enter a belly-button measurement here, you will get a higher body fat number, so use your natural waist. The Navy used these two spots with this formula until 2026. Its test today measures every Sailor’s waist at the belly button, women included, and uses that number in a different method (see US Navy Body Fat Standards below).

To get a good measurement, stand up straight, take a normal breath and either get someone to take your measurement or use a mirror to do it yourself.

Neck 

Measure the narrowest part of the neck, typically below the larynx also known as the Adam’s apple. 

Hip

Your hip measurement at its widest point.

Body Fat US Navy Formula 

Our body fat calculator opens on this same US Navy formula and also offers the YMCA, skinfold and BMI methods. Below we’ve included the body fat US Navy formulas for both men and women. All measurements are in centimeters; if you enter inches, the calculator converts them for you. 

Men’s formula

%BF = 495 / ( 1.0324 − 0.19077 * log10( waist − neck ) + 0.15456 * log10( height ) ) − 450

Women’s formula

%BF = 495 / ( 1.29579 − 0.35004 * log10( waist + hip − neck ) + 0.22100 * log10( height ) ) − 450

The Most Accurate Method For Measuring Body Fat

While the body fat US Navy calculator can give you a reasonable body fat and body composition estimate, it’s not the most accurate. It is one of the most convenient, though, and the Navy used tape measurements like these in its own body composition test until 2026. 

It’s also important to mention that even more advanced methods may not give you 100% accurate measurements but they can get very close and are pretty reliable. 

Tape and skinfold equations sit close together. Against a lab measurement, the typical error is about 3.5 percentage points for this Navy formula in men and 4.5 in women, and 3.4 points for the 3 and 7 site skinfold equations in men and 3.8 to 3.9 in women. The most accurate methods such as hydrostatic weighing and DEXA/DXA scan are more expensive to have done and require you to visit a facility that offers these more advanced technologies. 

While not as accurate but certainly acceptable, our body fat calculator is a very good and free-to-use option. Its BMI method needs no tools, but it cannot tell muscle from fat, so treat it as a rough guide. The other methods need a measuring tape or a skinfold caliper: for men the two come out about even, and for women the caliper is a little closer. 

The skinfold methods take a little more effort, and the result card lists every method your entries allow side by side, so you can compare them with your US Navy result.   

US Navy Body Fat Standards

The Navy’s body fat limits do not change with age. Since its 2026 update, the Navy checks Sailors’ body composition in two steps as part of its Physical Fitness Assessment (Guide-4, Body Composition Assessment, June 2026):

• Step 1, waist-to-height ratio: divide your waist, measured at the belly button for men and women, by your height. At 0.5499 or less you pass, and there is no step 2.
• Step 2, body fat estimate: at 0.55 or more, the Navy reads your body fat from its own tables, using your height minus your waist, and your weight. Above 26% for men or 36% for women, you are outside the standard, and the Navy records the whole Physical Fitness Assessment as a failure for that cycle, unless an exceptional score on the fitness test itself qualifies you for the Navy’s high-performance exemption.

The Navy no longer measures the neck or hips. Until 2026, the final step of its test (Guide-4, January 2025) estimated body fat from the neck and waist for men, and from the neck, waist and hips for women, with a woman’s waist taken at its narrowest point: the same measurements this calculator uses. Your result here is a body fat estimate. It does not tell you how you would score on the Navy’s current test, so check your waist-to-height ratio too. For the 5’10 man in the example above, a 32-inch waist gives 32 / 70 = 0.457, a pass at step 1.

To check your waist-to-height ratio against the Navy’s line, use the checker on our military body composition standards page.

Body Fat Categories Table

The category the calculator shows comes from this table, ACE’s body fat norms. The Navy’s limits in the section above (26% for men, 36% for women) sit above ACE’s Obesity line (25% for men, 32% for women), so you can land in the Obesity row here and still be inside the Navy standard.

You can also read your fat category as a health check. A high body fat percentage is often associated with being overweight, obese, out of shape, and/or prone to health risks. The good news is anyone can improve their body composition by hitting the weights and changing up their diet and overall lifestyle a little. 

Try these body composition exercises to build more muscle and shed fat. 

Are You US Navy Fit?

The Body fat US Navy calculator is convenient and easy to use whether you plan on serving in the US Navy or you simply want to measure your body fat percentage and body composition using this free tool. If you serve in the Navy or plan to, check your waist-to-height ratio as well, since that is the first step of the body composition test Sailors take today. 

While it may not be as precise compared to other body fat measuring methods, it doesn’t take much effort aside from hopping on the scale and measuring your waist and neck size (plus hips for women). 

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