Enter your height and weight in metric or imperial and get your Body Mass Index instantly — with the World Health Organization category and the healthy-weight range for your height.
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Body Mass Index (BMI) is a single number that relates your weight to your height. It is the most widely used quick screen for whether an adult's weight sits in a broadly healthy range for their height. The calculator above works in either unit system — type your numbers and the BMI, category and healthy-weight range update instantly.
| Units | Formula | Example |
|---|---|---|
| Metric | weight(kg) / height(m)² | 70 / (1.75)² = 22.9 |
| Imperial | 703 × weight(lb) / height(in)² | 703 × 154 / 69² = 22.7 |
Both formulas describe the same thing — the imperial version just folds in the 703 factor that converts pounds-and-inches into the metric result. This tool computes everything in metric internally and converts your imperial input for you, so the two agree.
These are the standard World Health Organization ranges for adults. They are general population thresholds and are not adjusted for age, sex, muscle mass or ethnicity.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obesity |
BMI is a screen, not a verdict. Because it uses only height and weight, it cannot tell muscle from fat — a lean, muscular athlete can read as "overweight," while someone with low muscle can read "healthy" while carrying excess fat. It is also less reliable for children and teenagers (who use age- and sex-specific percentiles instead), for older adults, during pregnancy, and across some ethnic groups where risk thresholds differ. Waist measurement, body-composition testing and a conversation with a healthcare professional give a fuller picture. Use your BMI as one useful data point, not the whole story.
Yes. Every calculation runs as plain JavaScript inside your browser — no server call, no upload, nothing logged or stored. Whatever height and weight you enter never leave your device. Refresh the page and it is gone.