BMI calculator
Calculate your Body Mass Index (BMI) using metric or imperial units to assess your healthy weight range. Based on WHO standards, BMI is a numerical value of your weight relative to height, categorized as underweight, normal, overweight, or obese. This tool processes data locally in your browser for complete privacy.
✨ Pro Tips for Best Results
- Waist Measurement: Use BMI alongside waist circumference. A waist over 35 inches (women) or 40 inches (men) indicates higher health risks regardless of BMI.
- Muscle Mass: If you lift weights regularly, your BMI may be high due to muscle, not fat. Focus on how your clothes fit.
- Age Factor: For older adults (65+), a slightly higher BMI (25-27) may actually be protective against frailty and bone loss.
BMI vs. Body Fat Percentage: Which is better?
BMI is a proxy measure. It doesn't measure body fat directly but correlates with it. Body fat percentage is more accurate but requires specialized equipment like skinfold calipers or DEXA scans.
For most people, BMI is a sufficient "first step" to identify potential weight-related health risks. However, if you are a high-performance athlete or bodybuilder, BMI will likely categorize you as "overweight" or "obese" because muscle is much denser than fat. In these cases, focus on body fat percentage and metabolic markers like blood pressure and blood sugar.
How BMI is calculated
Body Mass Index (BMI) is a numerical value derived from your weight and height, used as a screening tool for weight categories. The formula is BMI = weight (kg) / height (m)2. For imperial units: BMI = 703 × weight (lbs) / height (in)2.
Standard WHO categories: Underweight <18.5, Normal weight 18.5–24.9, Overweight 25–29.9, Obese ≥30. BMI is widely used because it requires no equipment and correlates reasonably well with body fat at the population level. However, it has known limitations: it cannot distinguish muscle from fat (athletes often show "overweight" BMI), doesn't account for fat distribution, and has different risk thresholds for different ethnicities (Asian populations face increased health risk at BMI >23). BMI is best used as one data point among many — including waist circumference, blood pressure, and blood markers — when assessing overall health.