Body Fat Calculator
US Navy circumference method — no calipers needed.
Last updated: January 2025 · Built for the 2024–25 financial year
Inputs
Results
Body fat
16.4%
Lean mass ratio
83.6%
Results are estimates only. For financial advice, consult a licensed adviser.
Overview
US Navy body-fat method using tape measurements
The US Navy circumference method, developed by Hodgdon & Beckett in 1984, estimates body-fat percentage from neck, waist (and hip for women) measurements. It correlates ±3-4% with DEXA scans — close enough for trend tracking at home.
It is the same method used to assess US Navy fitness compliance and is preferred over BMI for athletes and anyone with above-average muscle mass.
Formula
US Navy formula
Men: %BF = 86.010·log10(waist−neck) − 70.041·log10(height) + 36.76 Women: %BF = 163.205·log10(waist+hip−neck) − 97.684·log10(height) − 78.387
All measurements in cm. Take readings in the morning, relaxed, no flexing.
ACE healthy body-fat ranges
| Category | Men / Women |
|---|---|
| Essential fat | 2-5% / 10-13% |
| Athletes | 6-13% / 14-20% |
| Fitness | 14-17% / 21-24% |
| Acceptable | 18-24% / 25-31% |
| Obese | 25%+ / 32%+ |
Pro tips
- •Measure consistently — same time of day, same tape tension.
- •For accuracy, average three readings at each site.
- •Use as a trend, not an absolute. Direction beats precision.