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Body Fat Calculator

Estimate your body fat percentage from tape measurements using the U.S. Navy method, then see your fat mass and lean mass. Metric or imperial, updated as you type.

Sex

Units

Measure the neck below the larynx, the waist at the navel, and the hip at its widest point. Everything is calculated in your browser and nothing is uploaded.

Enter your height, neck, and waist to estimate your body fat.

How to calculate body fat percentage

  1. Pick sex and units

    Select male or female, then choose metric or imperial for your measurements.

  2. Enter your measurements

    Type your height, neck, and waist, plus your hip if you chose female. The body fat estimate appears the moment the measurements are valid; there is no button to press.

  3. Read and copy

    See your body fat percentage, its category, and, if you add your weight, your fat mass and lean mass. Use Copy summary to put the result on your clipboard.

Why use this tool

U.S. Navy circumference method

Works out body fat from height, neck, and waist, plus hip for women, using the Navy circumference formula. The estimate updates live as you type.

Fat mass and lean mass

Add your body weight and the result splits into fat mass and lean mass, the two figures most people track through a cut or a bulk.

Metric or imperial

Enter centimetres and kilograms, or switch to inches and pounds. Conversions happen internally and the answer is identical either way.

Body fat categories

Your result is placed on the standard body fat bands for your sex, from essential fat and athletes through fitness, average, and obese.

Your measurements stay on your device

Every figure is processed by the page alone. Nothing you enter is uploaded, stored, or logged.

About this tool

This body fat calculator estimates your body fat percentage from a few tape measurements using the U.S. Navy method, the circumference formula developed at the Naval Health Research Center. Enter your height, neck, and waist, plus your hip if you selected female, and the estimate appears as you type. It works in metric or imperial, converting your figures internally, and rounds the result to one decimal alongside a body fat category that runs from essential fat through to obese.

Add your body weight and the calculator also splits it into fat mass and lean mass, the numbers most people actually track through a cut or a bulk. The Navy method needs only a tape measure, so it is far more practical than calipers or a lab scan, though it is still an estimate: it reads body shape rather than measuring fat directly, and results drift if you measure at a different spot or pull the tape tighter. Measure the waist at the navel and the neck just below the larynx, keep the tape level, and stay consistent from week to week.

Your measurements never leave your device; the whole calculation happens on this page. For a quick weight-to-height screen you can pair it with the BMI calculator, and the unit converter handles standalone swaps such as inches to centimetres or pounds to kilograms.

Frequently asked questions

How does the U.S. Navy body fat method work?
It estimates body fat from body circumferences rather than skinfolds. For men it uses height, neck, and waist; for women it adds the hip. Those measurements go into the Navy formula, which reads body shape to approximate the proportion of fat, and the calculator applies it as you type.
How accurate is the Navy method?
For most people it lands within a few percentage points of a body composition scan, which is close enough to track a trend over weeks. It is less precise than methods like a DEXA scan or underwater weighing, and it can read high on very muscular builds. Treat it as a consistent estimate, not an exact medical measurement.
What measurements do I need and how do I take them?
You need height, neck, and waist, plus hip if you are female. Measure the neck just below the larynx, the waist at the navel, and the hip at its widest point. Keep the tape snug and level, do not compress the skin, and use the same spots each time so results stay comparable. Weight is optional and only needed for fat mass and lean mass.
Can I use inches and pounds?
Yes. Switch the units toggle to Imperial to enter height in feet and inches, the neck, waist, and hip in inches, and weight in pounds. Metric mode uses centimetres and kilograms. The tool converts internally, so both give the same body fat percentage.
Do I have to enter my weight?
No. Body fat percentage only needs your measurements, so you can leave weight blank. Add it if you also want fat mass and lean mass, which are your weight split into the part that is fat and the part that is not.
Are my measurements uploaded anywhere?
No. Everything is calculated in your browser. The measurements and weight you enter are never uploaded, stored, or logged.

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