複数の国際基準で体格指数（BMI）を計算。健康アドバイスと理想体重範囲を取得。純クライアントサイド。
体格指数（BMI）は、成人の低体重、過体重、肥満を分類するために一般的に使用される、身長に対する体重の単純な指数です。体重（kg）を身長（m）の二乗で割った値（kg/m²）として定義されます。この計算機は複数の国際分類基準をサポートし、個別の健康アドバイスを提供します。すべての計算はブラウザ内で実行されます — データはサーバーに送信されません。
BMI (Body Mass Index) is a simple measurement of body fat based on your height and weight. It is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). This calculator handles both metric and imperial units automatically.
According to the WHO standard, a healthy BMI range is 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is obese. Asian and China standards use slightly lower thresholds because research shows health risks begin at lower BMI values for these populations.
Different populations have different body compositions and health risk profiles. The WHO standard is designed for Western populations, while Asian and China standards account for the fact that people of Asian descent often experience obesity-related health risks at lower BMI values. This calculator lets you compare all three standards.
BMI is a useful screening tool but has limitations. It does not account for muscle mass, bone density, age, sex, or fat distribution. Athletes with high muscle mass may have a higher BMI despite low body fat. For a complete health assessment, consult a healthcare provider.
BMI is a weight-to-height ratio that estimates body fat. Body fat percentage is the actual proportion of fat in your body. BMI is easier to calculate and widely used, but body fat percentage provides a more accurate picture of body composition. Tools like body fat calipers or DEXA scans measure body fat percentage directly.
This calculator is designed for adults (18+). For children and teens, BMI is interpreted differently based on age and sex using percentile charts. Consult a pediatrician for accurate BMI assessment in children.
For general health monitoring, checking your BMI once every 3 to 6 months is sufficient. If you are actively working on weight management or fitness goals, you may check monthly. Daily changes are not meaningful — focus on long-term trends.
Consult a healthcare provider for personalized advice. General recommendations include adopting a balanced diet rich in vegetables and lean proteins, increasing physical activity (at least 150 minutes of moderate exercise per week), getting adequate sleep, and managing stress. Small, sustainable changes are more effective than extreme diets.