How this calculator works
It uses the U.S. Navy circumference equations, which estimate body density from your height, neck and waist (plus hips for women). It is the same approach many militaries use for fitness standards because it is cheap, fast and repeatable.
Body fat categories (American Council on Exercise ranges)
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
Measuring tips for consistent results
- Measure first thing in the morning, before eating.
- Use a flexible, non-stretch tape and take each measurement twice.
- Neck: just below the larynx, tape sloping slightly down to the front.
- Re-measure every 2 weeks — trends matter more than any single number.
FAQ
How accurate is the US Navy body fat method?
It is a practical estimate. Compared with lab methods like DEXA it is typically within a few percentage points for most people, but can be off more for very lean or very muscular bodies. Use it to track trends with consistent measurements.
How do I measure my waist correctly?
Men: measure horizontally at the navel. Women: measure at the narrowest point of the waist. Stand relaxed, exhale normally and keep the tape snug but not compressing the skin.
What body fat do you need for visible abs?
Roughly 10–12% for men and 16–19% for women for clear definition, with outlines often appearing a few points higher.