BMI計算機
身長と体重からBMI（体格指数）を即座に計算します。メートル法・ヤードポンド法の両方に対応。
身長と体重を入力するとBMIを計算します
BMI判定基準（WHO基準）
BMIはあくまでスクリーニング指標であり、診断結果ではありません。詳しくは医療専門家にご相談ください。
よくある問題
My BMI shows overweight but I exercise regularly — is that normal?
Yes. BMI does not account for body composition. Muscle is denser than fat, so athletes and people with high muscle mass often have a higher BMI despite low body fat percentage. In these cases, waist circumference or body fat percentage are more informative measures.
What is a healthy weight for my height?
Enter your height — the calculator automatically shows the weight range that corresponds to a Normal BMI (18.5–24.9). For example, for 170 cm height, the healthy range is approximately 53.5–72.0 kg (118–159 lbs).
How do I calculate BMI if I know my height in feet and weight in pounds?
Use the Imperial toggle at the top of the calculator. Enter your height in feet and inches in the two separate fields, and your weight in pounds. The tool converts to metric internally and shows your BMI using the standard formula.
What causes a BMI under 18.5?
A BMI below 18.5 is classified as Underweight, which can result from insufficient caloric intake, high metabolism, illness, or eating disorders. If you are underweight, a healthcare provider can help identify the cause and recommend a healthy approach to reaching a Normal BMI.
Can I use this BMI calculator for children or teenagers?
This calculator uses the adult BMI formula, which is not appropriate for people under 20. Children and teenagers require age- and sex-specific BMI percentile charts (CDC or WHO growth charts) because healthy BMI ranges differ by age and developmental stage.
BMI 計算機 とは？
The BMI Calculator computes your Body Mass Index — a widely used screening measure based on height and weight — in seconds. Enter your measurements in metric (kg and cm) or imperial (lbs, feet, and inches) and instantly see your BMI value, which WHO category it falls into, and the healthy weight range for your specific height.
A visual gauge shows where your BMI sits across the four categories: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30 and above). The tool also calculates the exact weight range that would bring you into the Normal category, making it practical for setting health goals.
BMI 計算機 の使い方
1. Select Metric (kg/cm) or Imperial (lbs/ft/in) using the toggle at the top.
2. Enter your height — for metric, enter centimeters; for imperial, enter feet and inches separately.
3. Enter your weight in kilograms or pounds.
4. Your BMI, category, and healthy weight range appear instantly — no button press needed.
5. The colored gauge shows your position across all four BMI categories visually.
使用例
Metric example:
Height: 175 cm Weight: 70 kg
BMI = 70 / (1.75 × 1.75) = 22.9 → Normal weight
Healthy range: 56.6 – 76.2 kg
Imperial example:
Height: 5 ft 9 in Weight: 154 lbs
BMI = 22.8 → Normal weight活用例
1. Personal health check: Quickly assess whether your current weight is in a healthy range for your height.
2. Goal setting: Use the healthy weight range output to set a concrete target weight for a fitness goal.
3. Family health: Calculate BMI for multiple family members using the metric/imperial toggle without reloading.
4. Pre-appointment prep: Note your BMI before a doctor's appointment to discuss weight-related health topics.
5. Travel health check: Use imperial or metric depending on which system you measured in locally.
よくある質問
Is BMI an accurate measure of health?
BMI is a useful population-level screening tool but has limitations for individuals. It does not distinguish between muscle and fat mass, so athletes may show a high BMI despite low body fat. It is best used as one data point alongside other health indicators.
What BMI is considered healthy?
The WHO defines a BMI between 18.5 and 24.9 as Normal weight for adults. Below 18.5 is Underweight, 25–29.9 is Overweight, and 30 or above is classified as Obese.
Does this use WHO or CDC BMI standards?
The calculator uses the WHO adult BMI formula and category thresholds (18.5 / 25 / 30), which are also used by the CDC for adults 20 years and older. Separate BMI charts exist for children and teens — this tool is for adults.
How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For imperial units, BMI = 703 × weight (lbs) ÷ height (inches)². The tool converts imperial input to metric internally before computing.