Step-by-Step Calculation (U.S. Navy Method)
- Measure your neck, waist, and (for women) hip circumference in inches or cm.
- Measure your height.
- Plug these into the Navy formula, which uses logarithms to estimate body density.
Worked Example
A man with a 38" waist, 15" neck, 70" height:
Body Fat % ≈ 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
= 86.010 × log10(23) − 70.041 × log10(70) + 36.76
≈ 86.010 × 1.362 − 70.041 × 1.845 + 36.76 ≈ 18.4% — a healthy, athletic range for an adult male.
Frequently Asked Questions
How accurate is the Navy method compared to a DEXA scan?
It's typically within 3-4% of lab-grade DEXA scan results for most people — accurate enough for tracking trends over time, though not precise enough for clinical diagnosis.
Should I measure at the same time each day?
Yes — measuring first thing in the morning before eating or drinking gives the most consistent, comparable results week to week.
