Estimate your body fat from three tape measurements using the US Navy method for men. It comes with a real error margin, shown honestly as a range, and is best used to track change over months. Nothing is stored.

Estimated body fat

16–26 % body fat

Midpoint estimate 21%. The spread is the method's real error, not false precision.

Your waist-to-height ratio is the number with guideline backing.

This uses the US Navy circumference method for men. It is free and repeatable, and it is only an estimate: tested against a three-compartment laboratory model it carried a total error of about 5 percentage points, so treat any single reading as a range. It is most useful for tracking change, measured by the same person, with the same tape, under the same conditions. For deciding whether your body composition is a health problem, the waist-to-height ratio is the better-supported number. This tool is information, not medical advice.

How it works

Enter height, waist and neck. The tool applies the US Navy circumference equation for men and shows the estimate as a range.

The formula and sources

It uses the Hodgdon and Beckett equation developed at the Naval Health Research Center in 1984: body fat percent equals 495 divided by (1.0324 minus 0.19077 times the log of waist minus neck, plus 0.15456 times the log of height), minus 450, with measurements in centimetres. Evaluated against a three-compartment laboratory model in men, it carried a standard error of about 4 percentage points and a total error of about 5, which is why the result is shown as a band rather than a single figure.

Assumptions

You are an adult man.
Tape is snug, level, and read after breathing out.
Waist is larger than neck, or the equation cannot resolve.

Limitations

This is an estimate from three tape measurements, not a body-composition scan. Its value is in tracking change over months with the same tape and the same technique. For a health judgement, the waist-to-height ratio has guideline backing and this number does not.

When to see a doctor

If your waist has grown steadily, or your waist-to-height ratio is 0.5 or above, ask for blood pressure, HbA1c and a lipid panel rather than another body-fat estimate.

Frequently asked questions

How accurate is the Navy body fat method?

Against a laboratory three-compartment model it carried a total error of about 5 percentage points in men. That is why the result here is a range, not a single number.

What is a good body fat percentage for men?

There is no single agreed cut-off, which is why this tool does not invent one. Use the waist-to-height ratio for the health judgement and this estimate for tracking direction.

Why do I need my neck measurement?

The equation uses the difference between waist and neck as its estimate of trunk fat, since the neck changes little as body fat changes.

How often should I measure?

Every four to six weeks, same tape, same time of day, same person measuring. Weekly readings mostly capture measurement noise.

Body Fat Calculator for Men (US Navy Method)