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BMI Calculator
Find your Body Mass Index in seconds — enter your height and weight, in metric or imperial, and see exactly where you sit and what a healthy weight for your height looks like.
✓ Free, no sign-up
✓ Metric & imperial
✓ Nothing is uploaded
Your measurements
Your result
22.9
kg/m²
Healthy
1418.5253040
UnderHealthyOverObese
The BMI categories
These are the standard adult categories used by the World Health Organization and the NHS.
| Category | BMI range | What it generally means |
|---|---|---|
| Underweight | Below 18.5 | You may not be getting enough nutrition; worth a chat with a doctor. |
| Healthy | 18.5 – 24.9 | The range linked with the lowest general health risk for most adults. |
| Overweight | 25 – 29.9 | Above the healthy range; small lifestyle changes can make a real difference. |
| Obese | 30 or above | Health risks rise further; a doctor can help with a safe, personal plan. |
How BMI is worked out
BMI compares your weight with your height. The formula is the same everywhere:
BMI = weight (kg) ÷ height (m)²
Example: 70 kg ÷ (1.75 m × 1.75 m) = 70 ÷ 3.0625 = 22.9
Example: 70 kg ÷ (1.75 m × 1.75 m) = 70 ÷ 3.0625 = 22.9
- Metric: divide your weight in kilograms by your height in metres, squared.
- Imperial: this tool converts feet/inches to centimetres and pounds to kilograms first, then uses the exact same formula — no rough "703" shortcut.
- Healthy weight range: for your height, it is the weight that gives a BMI of 18.5 at the low end and 24.9 at the high end.
⚠ Please read — what BMI cannot tell you
BMI is a screening guide, not a diagnosis. It is a quick population-level check, and it has real limits:
- It does not measure body fat and cannot tell muscle from fat — athletes and bodybuilders often score "overweight" while being perfectly healthy.
- It does not account for pregnancy, age, sex, ethnicity or where fat is stored (waist size matters too). Lower thresholds are often advised for people of South Asian, Chinese, African-Caribbean or Middle Eastern background.
- It is designed for adults. Children's BMI is judged differently, using age- and sex-specific charts.
If your result worries you — in either direction — talk to a doctor or another qualified health professional before making changes. They can look at the full picture; a single number cannot.