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Calculation Machine

Navy Body Fat Calculator

Body fat percentage from tape measurements.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Estimated body fat
16.4%
Lean mass share
83.6%

Quick answer

The US Navy circumference method estimates body fat from a log-based formula using neck, waist and hip measurements.

The formula

Men: %BF = 495/(1.0324-0.19077log10(waist-neck)+0.15456log10(height))-450

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • SexMale
  • Neck38 cm
  • Waist85 cm
  • Hip (women only)95 cm
  • Height178 cm

Result

  • Estimated body fat16.4%
  • Lean mass share83.6%

How to use the Navy Body Fat Calculator

  1. 1Measure neck, waist, and for women, hips, in centimetres.
  2. 2Enter your height in the same units.
  3. 3This is an estimate with roughly 3-4% error versus DEXA — do not use it for medical decisions.

Frequently asked questions

How accurate is the tape method?

It's a convenient field method, accurate to within a few percent for most body types.

Where do I measure waist?

At the narrowest point, or at the navel if there is no natural narrowing.

About this calculator

How the US Navy method works

The Navy method estimates body fat from height and circumferences: neck and waist for men, plus hips for women. It was developed to screen service members quickly and is still used because it needs only a tape measure.

Against DEXA scans it is typically within about 3–4 percentage points for most people. It tends to overestimate fat in very muscular people with thick necks less than it underestimates fat in people who carry weight around the hips.

Measuring correctly

  • Neck: just below the larynx, tape sloping slightly downward to the front.
  • Waist (men): at the navel. Waist (women): at the narrowest point.
  • Hips (women): at the widest point of the buttocks.
  • Measure relaxed, not sucking in, and repeat each reading twice.

Sources

More questions

Is the Navy method accurate?

It is reasonable for tracking trends; individual results can differ from lab methods by several percent.

Why does it use neck size?

Neck circumference reflects lean mass, helping separate muscular builds from higher body fat.