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Fill in the form and click Calculate BMI to see your personalized health report.
Enter your height and weight to receive your Body Mass Index score, WHO classification, ideal weight range, and daily water intake estimate — instantly.
Fill in the form and click Calculate BMI to see your personalized health report.
The World Health Organization defines the following standard weight classifications for adults (age 18+).
| BMI Range | Classification | Health Risk |
|---|---|---|
| Below 16.0 | Severe Thinness | Very high |
| 16.0 – 16.9 | Moderate Thinness | High |
| 17.0 – 18.4 | Mild Thinness | Moderate |
| 18.5 – 24.9 | Normal Weight | Low (ideal) |
| 25.0 – 29.9 | Overweight | Increased |
| 30.0 – 34.9 | Obese Class I | High |
| 35.0 – 39.9 | Obese Class II | Very high |
| 40.0 or above | Obese Class III | Extremely high |
Body Mass Index (BMI) is a medical screening tool that estimates body fat by comparing a person's weight to their height. It is used worldwide to categorize adults into Underweight, Normal Weight, Overweight, and Obese. BMI is useful for population-level assessments but is not a direct measure of body fat percentage.
BMI is computed by dividing your weight (in kilograms) by the square of your height (in meters):
For imperial units, the equivalent formula is:
BMI does not distinguish between muscle, fat, bone, and water. As a result:
Always consult a qualified healthcare provider for a complete health assessment.
BMI Prime is the ratio of your BMI to the upper boundary of the Normal range (25.0). A value below 1.00 means you are within or below the Normal range. A value above 1.00 indicates Overweight or Obese. It allows quick cross-population comparisons and is calculated as:
BMI is a useful baseline screening tool, not a diagnostic instrument. A complete health picture also includes waist circumference, blood pressure, cholesterol levels, blood glucose, and DEXA scan body composition measurements.
Yes. Muscle tissue is denser than fat tissue. Professional athletes or heavy lifters may score above 25 or 30 BMI despite having low body fat percentages — placing them in "Overweight" or "Obese" classifications incorrectly.
Yes. For adults over 65, a BMI between 23 and 27 is often considered protective against mortality. A BMI below 22 in elderly individuals may raise clinical concerns about malnutrition and bone density loss.
Once every few months is sufficient for tracking weight management trends. Daily checks are not recommended, as body weight fluctuates naturally due to water retention, digestion, and hormonal cycles.
This calculator is designed for adults (18+). Children and adolescents are evaluated using age-and-gender percentile growth charts — not static BMI ranges — because their body composition changes rapidly during growth.