Body Fat Calculator (US Navy Method)
Estimate your body fat percentage from your height and a few tape measurements. The calculator uses the US Navy circumference method and shows your category, fat mass and lean mass.
Measure with a soft tape on bare skin: the neck just below the larynx, the waist at the navel (men) or at its narrowest point (women), the hips at their widest point.
Your results
| Fat mass | 13 kg |
| Lean mass | 67 kg |
How it works
- 1Men measure height, neck and waist; women also measure the hips.
- 2The US Navy equations (Hodgdon and Beckett) turn these circumferences into a body fat percentage.
- 3If you enter your weight, we split it into fat mass and lean mass so you can track both over time.
Body fat percentage chart
Ranges used by the American Council on Exercise. Your result above uses the same bands.
| 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% and above | 32% and above |
Where these numbers come from
The formula is the circumference equation developed by Hodgdon and Beckett at the Naval Health Research Center and used by the US military: for men 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76, for women 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387, with all values in inches. It is an estimate, not a medical test; DEXA or underwater weighing are more precise.
Frequently asked questions
How accurate is the US Navy body fat method?
Against underwater weighing it is usually within about 3-4 percentage points. Careful, repeated measurements matter more than the exact number, so measure the same way each time.
What is a healthy body fat percentage?
For men about 14-24% falls in the fitness to average range, for women about 21-31%. Athletes are often lower, and essential fat is roughly 2-5% for men and 10-13% for women.
How do I measure my waist for body fat?
Men measure at the navel, women at the narrowest point of the waist. Stand relaxed, breathe out normally and keep the tape level without compressing the skin.
Is body fat percentage better than BMI?
It says more about body composition, because BMI cannot tell muscle from fat. Two people with the same BMI can have very different body fat.
Using the result
What the number is
An estimate from simple measurements: height, weight or a tape measure. These formulas describe large groups of people well and single bodies less well, because muscle, frame size and where you carry fat all shift the true value.
How to use it
Treat it as a reference point and follow the trend. Measure the same way and at the same time of day every two to four weeks, and look at the direction of change rather than a single reading.
When to stop guessing
If the number and the mirror disagree for months, track your waist, photos and strength alongside it. A coach on Trainera reads them together and adjusts your plan.
What this calculator cannot know
This calculator works from height, sex and, depending on the tool, your weight or a few circumferences. BMI and ideal weight cannot tell muscle from fat, and a tape measure estimate can be off by several percentage points even when you measure carefully. None of them account for ethnicity or bone structure, and they are not meant for children, pregnant women or very muscular athletes. Use the result as a rough reference and talk to a doctor if you are worried about your weight. Nothing here is medical advice.
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Turn these numbers into a real plan
Train on your own with Trainera's free workout and diet tracker, or get matched with a certified personal trainer who builds your plan around these numbers.