Body Fat Percentage Calculator
Navy circumference formulas — not DEXA or a clinic test. Click any i for detail.
Tape measurements
Sex
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Sex
Chooses the male or female Hodgdon/Beckett formula the Navy tape method uses. |
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Height (in)
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Height
Standing height in inches. |
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Neck (in)
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Neck
Just below the larynx, tape level. |
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Waist (in)
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Waist
Men: at navel. Women: smallest waist. Tape level, relaxed. |
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Hip (in)
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Hip
Widest point. Used in the female formula; ignored for male. |
How to use this calculator
- Pick male or female formula.
- Enter height and neck.
- Enter waist (and hip if female).
- Treat the % as a tape estimate, not a diagnosis.
Results explained
Male: 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76. Female: 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. Inches throughout.
Quick reference: Navy tape
Circumferences must stay geometrically valid (waist larger than neck).
| Item | Detail |
|---|---|
| Male tautology | Uses waist − neck |
| Female tautology | Uses waist + hip − neck |
| Not BMI | BMI is a different page we have not shipped |
| Calipers / DEXA | Not this formula |
Military body-composition policies change — this is the classic tape math.
How the estimate is built
Hodgdon/Beckett log10 circumference equations (U.S. Navy method).
Example scenario
Male 70 in, 16 in neck, 34 in waist → a mid-teens/low-20s tape % depending on the logs — read the live result.
FAQ
Why hip on men?
The male formula does not use hip. Enter it anyway; it is ignored.
Is this medical?
No. Unusual results → talk to a clinician, don’t chase the tape.
Lean mass?
Not converted here.