Interactive tool
Body-Fat Percentage Calculator (US Navy Method)
Body-fat percentage tells you something the scale and BMI cannot: how much of your body is fat versus lean tissue. This calculator uses the US Navy circumference method, which needs only a tape measure, to estimate it. It is a useful way to track the trend of your composition over time, especially while losing weight, when the goal is to lose fat and keep muscle.
Body-Fat % Estimator
Enter your measurements to estimate body fat.
Ranges for men
Athletic
6 - 13%
Fitness
14 - 17%
Average
18 - 24%
High
25%+
Uses the US Navy circumference method: measure the neck below the larynx, the waist at the navel, and (for women) the hip at the widest point. It is a tape-measure estimate, handy for tracking a trend over time, and less precise than a DXA or hydrostatic measurement. Not medical advice.
Weight alone is a blunt measure. Two people at the same weight and height can have very different amounts of fat and muscle, and the scale cannot tell them apart. Body-fat percentage can, and this calculator estimates it from three or four tape-measure readings using a method developed and validated by the US Navy.
How the Navy method works
The technique uses body circumferences that correlate with fat distribution: the neck and waist for men, plus the hip for women, all set against height. It runs those measurements through a validated formula to estimate the percentage of your body that is fat. Because it needs only a tape measure, you can do it at home and repeat it as often as you like, which is what makes it useful for tracking.
Why composition matters more than weight on a GLP-1
On a GLP-1 the aim is to lose fat while keeping muscle, because muscle supports strength, metabolism, and long-term weight maintenance. The scale hides this distinction. Tracking body-fat percentage alongside weight shows whether your loss is mostly fat, which is the goal, or whether you may be shedding lean mass and should lean harder on protein and resistance training. Our piece on how muscle affects metabolism explains why keeping it matters.
Measuring well
Accuracy depends on consistent measurement. Use a flexible tape on bare skin, snug but not digging in. Measure the neck just below the larynx, the waist at the navel, and, for women, the hip at its widest point, keeping the tape level all the way around. Take each reading a couple of times and average them. Measuring the same way each session matters more than any single number, because the trend is what you are really tracking. For setting expectations on how fast that trend should move, see our guide to realistic weight-loss goals.
What it is and is not
This is an estimate, useful for trends, not a clinical measurement. DXA and hydrostatic weighing are more precise, and the formula is less reliable at the extremes of body composition. Use the number as a consistent yardstick rather than an exact truth, and pair it with how your clothes fit and how you feel. Not medical advice.
Frequently Asked Questions
How accurate is the US Navy body-fat calculator?
It is a reasonable estimate, typically within a few percentage points of a DXA scan for most people, and its real strength is consistency: measured the same way each time, it tracks your trend well. It is less accurate than DXA or hydrostatic weighing, so treat the exact number as approximate and watch the direction over time.
How do I measure for the calculator?
Use a flexible tape measure on bare skin, snug but not compressing. Measure the neck just below the larynx, the waist at the navel, and, for women, the hip at its widest point. Keep the tape level and take each measurement two or three times, using the average, for the most reliable result.
Why track body fat instead of just weight on a GLP-1?
Because the goal is to lose fat while keeping muscle, and the scale cannot tell the two apart. Tracking body-fat percentage alongside weight shows whether your loss is coming mainly from fat, which is what you want, or whether you may be losing too much lean mass and should focus more on protein and resistance training.
What is a healthy body-fat percentage?
Ranges differ by sex. For men, roughly 6 to 13% is athletic, 14 to 17% is fitness, 18 to 24% is average, and 25% or more is high. For women, about 14 to 20% is athletic, 21 to 24% is fitness, 25 to 31% is average, and 32% or more is high. These are general references, not medical thresholds.
Not medical advice. This resource is for general education only. Medications, dosing, and treatment suitability are decisions for you and a licensed clinician who knows your full medical history.
Last updated · 5 min read
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