Tool
Body fat calculator (Navy method)
Three tape measurements: height, neck, waist. The U.S. Navy circumference method is the standard way to estimate body fat without scales, calipers, or a lab. Calculate, then see the visual reference for your exact percent.
Estimated body fat
16.4%
See what 16% looks like →Tape-measure method: typical error is ±3% vs a DEXA scan. Good enough for tracking direction, not for bragging rights.
Where this method is reliable — and where it isn't
The Navy formula was fitted against underwater weighing using circumference correlations. It works decently for the typical male pattern (fat stored at the waist), but drifts for very muscular builds or atypical fat distribution. Expect ±3% versus a DEXA scan. The right way to use it: same time of day (fasted morning), same tape, every 2-4 weeks, and track the trend — the trend is worth far more than the absolute number.
After the number: see the visual reference
A percent on its own is abstract. Every percent from 6 to 35 has its own page: what it actually looks like on a man, how visible the jawline and outline are, and what it does to the first-glance read.
Go to the body-fat visual index →Got your body fat? Compute FFMI next
Body fat is the required input for FFMI (Fat-Free Mass Index) — the natural-lifter yardstick for how much muscle you actually carry.
Go to the FFMI calculator →Body fat is one input of the first glance
1 minute. The AI combines physique × face × outfit and reads what the 1.2-second first impression actually registers — plus your ceiling.