No calipers, no DEXA scan — just a flexible tape measure. Takes about 60 seconds.
Measure just below the larynx, perpendicular to the neck's long axis.
Measure at the widest point.
—%
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Estimated body fat — ±3–4% accuracy
EssentialAthleteFitnessAcceptableObese
Fat mass—
Lean mass—
Estimate only. The U.S. Navy method has a typical error of ±3–4 percentage points. For medical decisions, use DEXA or hydrostatic weighing. ACE category ranges are sex-specific.
How to take the measurements
1
Neck: Hold the tape just below the larynx. Keep the tape perpendicular to the neck's long axis. Don't compress the skin.
2
Waist (male): Measure at navel level, horizontally. Exhale normally before measuring — don't hold your breath in.
3
Waist (female): Measure at the narrowest point of the torso, usually just above the navel.
4
Hip (female only): Measure at the widest point of the hips and buttocks, keeping the tape horizontal.
Track body composition in FitMagic
Log body measurements over time and let your AI coach connect body composition trends to your training and nutrition.