Calculate your body fat percentage using the U.S. Navy Method. Find out your lean mass and fat mass instantly.
Use a tape measure for accuracy.
This guide is for educational purposes and is not medical advice. See our Disclaimer and consult a qualified healthcare professional before making changes to your diet or exercise routine.
Body fat percentage is the share of your total body weight that comes from fat, as opposed to muscle, bone, water, and organs. If you weigh 160 pounds and have 24 pounds of fat, your body fat percentage is 15%. It is one of the clearest ways to describe what your weight is actually made of.
This matters because the scale alone cannot tell muscle from fat. Two people can weigh exactly the same yet look and function completely differently depending on their composition. That is also the main weakness of BMI, which only compares weight to height. A muscular athlete can land in the "overweight" BMI range while carrying very little fat. Tracking body fat percentage gives you a more honest picture of your health, your fitness, and the results of your training or diet.
This tool uses the U.S. Navy circumference method, developed by researchers Hodgdon and Beckett for the U.S. Navy. Instead of expensive equipment, it estimates body fat from a few tape-measure readings and your height. The idea is that fat and lean tissue are distributed in predictable patterns, so the relationship between your waist, neck, and height (plus hips for women) closely tracks how much fat you carry.
The formula uses different equations for men and women. For men, it works from the waist and neck measurements relative to height. For women, it adds the hip measurement, because women naturally store more fat around the hips and thighs. A larger waist relative to the neck generally points to a higher body fat percentage. All measurements in this calculator are entered in inches and pounds, and the math is handled instantly as you type.
Fill in the fields on the measurement panel and your results update automatically. Here is what each input needs:
Measuring tip: Use a flexible cloth or vinyl tape, not a stiff metal one. Keep the tape snug against the skin but not so tight that it compresses it. Take each measurement two or three times and use the average, and try to measure in the morning before eating for the most consistent day-to-day readings.
Say a man weighs 180 pounds, stands 70 inches tall, and measures a 16-inch neck and a 34-inch waist. Feeding those numbers into the Navy formula returns roughly 15% body fat. From there the calculator does the rest: 15% of 180 pounds is about 27 pounds of fat mass, which leaves around 153 pounds of lean mass. That single reading places him in the "fitness" range and gives him a clear baseline to track as he trains.
The table below shows widely used body fat norms from the American Council on Exercise (ACE). Ranges differ by sex because women carry more essential fat than men.
| Category | Women | Men |
|---|---|---|
| Essential Fat | 10-13% | 2-5% |
| Athletes | 14-20% | 6-13% |
| Fitness | 21-24% | 14-17% |
| Average | 25-31% | 18-24% |
| Obese | 32%+ | 25%+ |
Not all body fat is a problem. Your body actually needs a baseline amount to survive:
This is why the healthy ranges differ by sex. Women carry more essential fat, largely to support reproductive function, so a body fat percentage that is perfectly healthy for a woman would be considered low for a man. Comparing yourself only to your own sex-specific range is the right approach.
The Navy method is a solid estimate, not a lab measurement. Studies generally place it within about 3-4% of body fat for most people, which makes it far more useful than BMI and accurate enough to track progress over time. Its accuracy depends heavily on consistent, careful measuring, so small tape errors can shift the result.
Because it relies on circumferences, it can be less accurate for people at the extremes, such as very lean athletes, those with a lot of muscle, or people carrying significant fat. Gold-standard methods like a DEXA scan or hydrostatic (underwater) weighing are more precise but require specialized equipment and cost money. For everyday tracking at home, the most useful habit is to measure the same way each time and watch the trend rather than fixating on a single number.
Your body fat percentage is a starting point, not a verdict. If you want to change it, the next step is building a plan around the right calorie and macronutrient targets, then choosing meals you can stick with.
For men, 14-17% is considered 'fit', while 18-24% is acceptable. For women, 21-24% is 'fit', and 25-31% is acceptable. Athletes typically have lower percentages.
The Navy Method is widely accurate within 3-4% for most people. It is generally more reliable than BMI but less precise than a DEXA scan.
Measure at the navel (belly button), not the narrowest part. Keep the tape level and snug but not tight. Breathe out naturally before measuring.
The U.S. Navy formula uses different equations for each sex. Because women naturally carry more fat in the hip and thigh region, the female formula adds the hip circumference to improve accuracy. The male formula relies on waist and neck alone.
For assessing body composition, yes. BMI only compares weight to height and cannot tell muscle from fat, so a lean, muscular person can be labeled overweight. Body fat percentage estimates how much of your weight is actually fat, giving a clearer picture of health and fitness.
Yes. Dropping below the essential fat level (roughly 2-5% for men and 10-13% for women) can disrupt hormones, temperature regulation, and organ function. In women it can affect menstrual and reproductive health. Very low body fat is not a healthy long-term goal for most people.
Every two to four weeks is enough to track a trend. Body fat changes slowly, and day-to-day shifts usually reflect water, food, and measurement variation rather than real fat loss. Measure at the same time of day under similar conditions for the most consistent results.
Essential fat is the minimum your body needs to function, protecting organs, nerves, and hormone production. Storage fat is the energy your body banks in fat tissue under the skin and around the organs. A healthy body fat percentage keeps essential fat intact while holding storage fat in a moderate range.
The information on this page is based on guidance from the following authoritative sources:
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