Body Fat Calculator (US Navy Method)
Estimated body fat percentage, fat mass and lean mass from neck, waist, hip and height measurements.
Results
What this tool does
The US Navy circumference method was developed so that body composition could be assessed with a tape measure and nothing else, and it has survived because it works reasonably well for reasonably ordinary bodies. Enter 1 for men and 0 for women — the two formulas are genuinely different, and the women's version uses the hip measurement while the men's does not.
Formula
men: 86.010 log₁₀(waist − neck) − 70.041 log₁₀(height) + 36.76 (in inches)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
sx | Sex | — |
wa | Waist circumference | cm |
nk | Neck circumference | cm |
hp | Hip circumference | cm |
ht | Height | cm |
kg | Body weight | kg |
BF | Body fat | % |
FM | Fat mass | kg |
LM | Lean body mass | kg |
Worked example
- Sex1
- Waist circumference90 cm
- Neck circumference38 cm
- Hip circumference95 cm
- Height178 cm
- Body weight80 kg
- Body fat20.27 %
- Fat mass16.21 kg
- Lean body mass63.79 kg
Limitations
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- US and imperial (UK) units with the same name are not the same size. Check which system your figures come from.
Frequently asked questions
How accurate is the tape measure method?
Studies put it within about three to four percentage points of a DEXA scan for most people, which is good enough to track a trend and not good enough to argue over a single reading. It is least reliable at the extremes — very lean or very heavy — and it is sensitive to where you place the tape, so measure at the same landmarks every time and compare like with like.