Why logarithms?
The Navy regression fit uses log terms to linearize circumference relationships.
US Navy Body Fat Calculator
Official-style Navy body fat formula using neck, height, and waist (men) or waist+hip (women) in inches.
Circumference measurements
Measure in inches. Men: abdomen at navel; women: waist at narrowest, hip at widest.
About this calculator
How to use US Navy Body Fat Calculator, plus the formulas and logic behind the results.
Tool description
The U.S. Navy method estimates body fat from circumference measurements and height using logarithmic equations—common in military fitness assessments.
How to use
- Measure neck below larynx, tape sloping slightly down.
- Men measure abdomen; women measure waist and hip.
- Enter height and all required circumferences.
- Review estimated body fat percentage.
Formulas & reference
Men: 86.010×log₁₀(abdomen−neck) − 70.041×log₁₀(height) + 36.76Women: 163.205×log₁₀(waist+hip−neck) − 97.684×log₁₀(height) − 78.387All lengths in inches
Measurement tips
- Stand relaxed, arms at sides
- Tape parallel to floor
- Snug contact, not compressing skin
- Same time of day for repeat checks
Calculation logic
Height converts to inches, sex-specific Navy log equation applied, result clamped to 3–60%.
Tape technique matters. One bad measurement skews log terms noticeably.
US Navy Body Fat Calculator FAQ
Common questions about this calculator and how to use the results.
Do I need calipers?
No—this method uses tape only.
Men enter waist?
Men use abdomen at navel level per Navy protocol.
Flexed abs?
Measure relaxed—flexing cheats the reading.
Compared to DEXA?
Can differ by several percentage points; good for tracking with consistent technique.
Metric height OK?
Yes—converted to inches internally.