Estimate your body fat percentage using the standard US Navy circumference-based equations. Supports both US Imperial and Metric systems.
Recent Calculations
How to Interpret Your Results
Understanding the US Navy Circumference Method
The US Navy Body Fat formula is a widely accepted method to estimate body fat percentage without using expensive equipment like DEXA scans or hydrostatic weighing. It relies on standard anatomical circumferences that track closely with subcutaneous and visceral fat deposits.
Measuring Guidelines
To get the most accurate results, use a flexible, non-stretchable tape measure:
- Height: Measured without shoes.
- Neck: Measure just below the larynx (Adam’s apple), wrapping horizontally.
- Waist:
- Men: Measure horizontally at the level of the navel.
- Women: Measure horizontally at the narrowest part of the abdomen (usually just above the navel).
- Hips (Women only): Measure horizontally at the widest part of the glutes.
Standard Categories (ACE Guidelines)
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
The Math Behind It
The tool uses the following mathematical principle:
$$ \begin{aligned} \text{BFP}{\text{male}} &= 86.010 \log{10}(W - N) - 70.041 \log_{10}(H) + 36.76 \ \text{BFP}{\text{female}} &= 163.205 \log{10}(W + Hp - N) - 97.684 \log_{10}(H) - 78.387 \end{aligned} $$
Where:
- $W$ is the Waist Circumference (inches).
- $N$ is the Neck Circumference (inches).
- $H$ is the Height (inches).
- $Hp$ is the Hip Circumference (inches, females only).
- Note: If Metric units are entered, they are converted to inches ($ ext{inches} = ext{cm} / 2.54$) before computing.