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Health and fitness formula

How to calculate navy body fat

The Navy body fat method uses a tape measure estimate rather than a lab test.

See the formulaOpen calculator
Direct answer
Formula
male: BF% = 495 / (1.0324 - 0.19077log10(waist - neck) + 0.15456log10(height)) - 450

Use the table below to match each symbol with the right input. Keep units consistent before you start.

Navy body fat formula
Start here when you only need the equation and variable names.
Formula
male: BF% = 495 / (1.0324 - 0.19077log10(waist - neck) + 0.15456log10(height)) - 450

The Navy body fat method uses a tape measure estimate rather than a lab test.

Variable meanings
Check each symbol, meaning, and unit before you calculate.
SymbolNameDescriptionUnit
waistWaistWaist circumference.cm or in
neckNeckNeck circumference.cm or in
hipHipHip circumference used in the female equation.cm or in
heightHeightBody height.cm or in
When to use this formula
Check that your situation matches the formula before you trust the result.
  • This estimate works best when waist, neck, hip, and height measurements are taken the same way each time.
Step-by-step method
Follow these steps when you are solving it by hand.
  1. 1Measure height, waist, neck, and hip when required.
  2. 2Use the male or female Navy equation.
  3. 3Keep all length measurements in the same unit system.
  4. 4Round the final percentage after the calculation.
Examples
These sample numbers show the order of operations and units.
Male Navy estimate
waist
86 cm
neck
40 cm
height
178 cm
  1. 1.BF% = 495 / (1.0324 - 0.19077log10(86 - 40) + 0.15456log10(178)) - 450
  2. 2.BF% = 15.7%
Result
The body fat estimate is about 15.7%.
Female Navy estimate
waist
75 cm
hip
98 cm
neck
34 cm
height
165 cm
  1. 1.BF% = 495 / (1.29579 - 0.35004log10(75 + 98 - 34) + 0.221log10(165)) - 450
  2. 2.BF% = 27.9%
Result
The body fat estimate is about 27.9%.
Mistakes to avoid
Small input or unit errors can change the answer a lot.
  • Treating the navy body fat result as a diagnosis or a personal training plan.
  • Mixing inches, centimeters, pounds, and kilograms without converting first.
  • Using stale measurements after weight, activity, or training level changes.
  • Ignoring the method assumptions behind the estimate.
Open the Body Fat Calculator
Open the calculator for the answer without rewriting the formula.

Enter your values in the related calculator, then compare the output with the hand method above.

Open Body Fat Calculator
FAQs
Short answers for common formula questions.
Is the Navy body fat formula a medical test?

No. It gives an estimate from a few inputs. Treat it as a planning or screening number, and ask a qualified clinician about symptoms, medication, pregnancy, eating disorders, or medical conditions.

Why can my Navy body fat result differ from a wearable or lab test?

Different methods use different assumptions. Small measurement changes, activity estimates, and rounding can move the result.

Can I use the Body Fat Calculator instead?

Yes. The Body Fat Calculator handles the arithmetic and helps catch unit conversion mistakes.