BMI Calculator
Calculate your Body Mass Index quickly and understand what your result means.
Calculate your BMI
Enter your details below. Nothing you type here leaves your device — the calculation runs entirely in your browser.
About BMI for people under 18
Standard adult BMI categories (underweight, normal, overweight, obesity) don't directly apply to children and teenagers. Pediatric BMI is typically interpreted using age- and sex-specific BMI percentiles compared against growth charts, since healthy body composition changes as children grow. This calculator does not provide a pediatric diagnosis or percentile assessment — a pediatrician or healthcare provider is the right resource for interpreting a young person's BMI.
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What is BMI?
Body Mass Index (BMI) is a simple screening number that compares your weight to your height. It's widely used as a quick, low-cost way to get a general sense of whether someone's weight falls in a typical range for their height — nothing more, nothing less.
BMI doesn't measure body fat directly, and it doesn't account for muscle, bone density, or where fat is distributed on the body. It's a starting point for a conversation, not a verdict.
How is BMI calculated?
The standard adult formula divides weight in kilograms by height in metres, squared:
BMI = weight (kg) ÷ height (m)²
If you're using pounds and inches, the calculator above converts your numbers automatically — you don't need to do any unit math yourself.
BMI categories
| BMI range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
What does my BMI mean?
Underweight may suggest insufficient energy intake relative to needs, though it can also reflect body type, activity level, or other factors — it's worth discussing with a healthcare provider if it concerns you.
Normal weight falls within the range most commonly associated with lower weight-related health risk at a population level, though individual health depends on many other factors.
Overweight and obesity categories are associated, at a population level, with higher likelihood of certain health considerations — but BMI alone cannot tell you about your individual health status.
Healthy weight range
The estimated healthy weight range shown in your results is calculated by applying the standard adult BMI boundaries (18.5 and 24.9) to your entered height. It's a mathematical estimate, not a personalized medical recommendation — your ideal weight depends on your body composition, muscle mass, age, and overall health.
Limitations of BMI
- BMI does not directly measure body fat percentage.
- It cannot distinguish muscle mass from fat mass — muscular individuals may score higher without excess body fat.
- It may not accurately represent health for every body type, age group, or population.
- It is a screening measure, not a diagnostic tool.