Body-fat percentage tells you what the scale can't: how much of your weight is fat versus everything else. The US Navy method estimates it from simple tape measurements — no calipers, no lab — and tracks change over time remarkably well.
工作原理
Measure your neck and waist (and hips, for women) with a tape, plus your height. The calculator plugs these circumferences into the Navy's logarithmic regression formulas, developed and validated on large military populations.
公式
All measurements in cm; log is base-10. For women the formula uses waist + hip − neck. Measure the waist at the navel, the neck below the larynx, relaxed and without pulling the tape tight.
计算示例
A man 170 cm tall with a 38 cm neck and 85 cm waist: waist − neck = 47, and the formula returns about 17.8% body fat — within the 'fitness' range for men.
常见问题
What are healthy body-fat ranges?
Commonly cited adult ranges: men — athletes 6–13%, fitness 14–17%, acceptable 18–24%; women — athletes 14–20%, fitness 21–24%, acceptable 25–31%. Essential fat minimums are ~3% for men and ~12% for women.
How accurate is the tape method?
Typically within ±3–4% of lab methods like DEXA. Its real strength is consistency: measured the same way at the same time of day, it tracks your trend reliably even if the absolute number is slightly off.
Why is my BMI normal but body fat high (or vice versa)?
BMI can't distinguish muscle from fat. A muscular person can be 'overweight' by BMI with low body fat, while a sedentary person can be 'normal' weight with high fat — which is exactly why this measurement complements BMI.
An estimate for tracking purposes, not a clinical measurement. For medical assessment, consult a healthcare professional.