Everyday Tools
Body Fat Calculator
US Navy tape-measure method with honest error bars and bands.
✓ Free
✓ No account
◉ Runs on this device
Everyday Tools
Powering up the tool…
TOOL BODY-FAT-CAL
What this tool does
About the body fat calculator
Circumference formula, measurement discipline, and trend-over-reading advice.
How to use it
- Measure neck, waist (navel level) — and hips for the female formula.
- Enter with your height and units.
- Read the estimate and band.
- Repeat same-time same-tape weekly; watch the TREND.
Useful for
- Estimate body fat without callipers or scans.
- Track a trend with a repeatable method.
- Get the band, not just the digits.
Straight answers
Body Fat Calculator FAQ
How accurate is a tape measure method?
±3–4% against lab methods for typical builds — worse at extremes. The single reading is coarse; the weekly trend is genuinely informative, which is how the Navy uses it too.
Why does the female formula need hips?
Fat distribution differs, and the validated regression uses waist+hip−neck for women versus waist−neck for men. Using the wrong variant produces confident nonsense, so the tool asks.