Enter your height and weight in metric or imperial units to calculate your Body Mass Index. Everything is calculated instantly in your browser — nothing is uploaded or stored.
Age and sex don't change the BMI formula itself, but they do change how the result should be interpreted — see the notes below.
Switch between metric (cm/kg) and imperial (ft-in/lb) depending on what's easiest for you.
Your BMI, category and position on the scale update instantly as you type.
Understand the category and its limitations, then consider it alongside your medical history and other health information.
BMI is a screening tool. Combine it with how you feel, your activity level, and a conversation with a healthcare provider if you have concerns.
| BMI range | Category | General meaning |
|---|---|---|
| Below 18.5 | Underweight | May indicate insufficient energy intake relative to needs |
| 18.5 – 24.9 | Healthy weight | Associated with lower average health risk in most populations |
| 25 – 29.9 | Overweight | Associated with somewhat higher average health risk |
| 30 and above | Obese | Associated with higher average health risk; often broken into further classes |
These are general population-level associations, not individual predictions. Read more in our guide to BMI categories explained and why BMI isn't perfect.
Estimate your daily energy needs based on activity level.
Coming soonA simple tape-measure-based body fat estimate.
Coming soonA general daily hydration guide based on weight and activity.
Coming soonTurn a calorie target into protein, carb and fat grams.
Coming soonBMI is a useful, quick screening tool at a population level, but it has real limitations for individuals — it doesn't distinguish muscle from fat, and doesn't account for age, sex, or body composition. We break this down fully in why BMI isn't perfect.
Not reliably. Athletes and very muscular people often show a higher BMI despite having low body fat, since muscle is denser than fat. See our guide on BMI for athletes and muscular people.
Yes. Child and teen BMI is interpreted using age- and sex-specific percentile charts rather than the fixed adult categories used on this page. This calculator is designed for adults.
No. The calculation happens entirely in your browser using JavaScript. Nothing you enter is sent to or stored on our servers.
Use it as one data point, not a verdict. If your result is outside the "healthy weight" range and you have questions or concerns, a doctor or registered dietitian can give you a full, personalized picture that a single number can't.
For 68 kg and 170 cm, convert height to 1.70 m, then divide 68 by 1.70 squared. The result is about 23.5. A category is a screening reference, not a diagnosis or a prescribed goal weight.
This calculator uses adult categories for people aged 20 and older. Children and teens need age-specific assessment; pregnancy and individual medical circumstances require different interpretation.
Read the checklist: what to do after a BMI result · CDC’s explanation of BMI