Body Fat Calculator

The US Navy tape method has a margin of error of ±3–4% compared to DEXA scans (the gold standard). It's more accurate than BMI for estimating body composition, and far more accessible than underwater weighing or DEXA. Consistency in measurement technique matters more than absolute accuracy.

Men measure at the navel (belly button). Women measure at the narrowest point between the bottom of the rib cage and the top of the hip bones (natural waist). Always measure at the same time of day — body circumferences fluctuate with food, water, and bloating.

Healthy ranges increase slightly with age: men under 40: 8–19%; men 40–59: 11–21%; men 60+: 13–24%. Women under 40: 21–32%; women 40–59: 23–33%; women 60+: 24–35%. Athletes typically fall 5–8 percentage points below these ranges.