以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Measure your neck just below the larynx, sloping slightly downward.
- Measure your waist horizontally at the navel for men, or at the narrowest point for women.
- Women also measure the hips at the widest point of the buttocks.
- Enter the measurements with your height, weight, age and sex.
計算式
The US Navy method (Hodgdon and Beckett, 1984) estimates body density from circumferences and height. A BMI-based estimate (Deurenberg) is shown for comparison.
Men: BF% = 495 / (1.0324 − 0.19077 log₁₀(waist − neck) + 0.15456 log₁₀(height)) − 450
Women: BF% = 495 / (1.29579 − 0.35004 log₁₀(waist + hip − neck) + 0.22100 log₁₀(height)) − 450
Example
- Man, 175 cm, neck 38 cm, waist 88 cm.
- log₁₀(50) = 1.69897; log₁₀(175) = 2.24304.
- BF% = 495 / (1.0324 − 0.32411 + 0.34668) − 450 ≈ 19.2%.
よくある質問
How accurate is the Navy method?
It typically estimates within 3–4 percentage points of laboratory methods such as DEXA, provided the measurements are taken carefully. Measure 2–3 times and average.
What body fat percentage is healthy?
The American Council on Exercise considers about 14–24% average to fit for men and 21–31% for women. Essential fat is about 2–5% for men and 10–13% for women.
Why does my result differ from my smart scale?
Bioelectrical impedance scales are affected by hydration, food and time of day. Each method has its own error, so track trends rather than single readings.