BMI Calculator
Calculate body mass index from height and weight, see which BMI category the result falls into, and view the healthy weight range for your height.
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- Free · no sign-up
Body mass index
23.5
Healthy weight
BMI doesn't distinguish muscle from fat, so it reads high for very muscular people. Treat it as a screening number, not a diagnosis.
What BMI measures
Body mass index divides weight by height squared. In metric units that's
kg ÷ m²; in imperial it's lb ÷ in² × 703. The result is a single number that
places you on a scale designed to flag weight that may affect health.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and above | Obese |
These thresholds come from the World Health Organization and apply to adults.
What BMI does not measure
BMI knows nothing about body composition. It can't tell muscle from fat, and it ignores where fat sits on the body — which matters more for health risk than the total. The practical consequences:
- Muscular people frequently score as overweight or obese despite low body fat.
- Older adults may lose muscle while keeping the same BMI, masking a real change.
- Ethnicity shifts the thresholds. Health risks appear at lower BMI values in South Asian and East Asian populations, and several countries use adjusted cut-offs of 23 and 27.5.
Better used alongside other numbers
Waist circumference and waist-to-height ratio capture abdominal fat, which is the part most strongly linked to metabolic risk. A useful rule of thumb: keep your waist under half your height.
Children and teenagers
Under-18s are assessed against age- and sex-specific percentile charts rather than fixed thresholds, because healthy body composition changes rapidly during growth. Adult categories don't apply.
How to use the BMI Calculator
Three steps, no sign-up.
Choose metric or imperial
Centimetres and kilograms, or feet, inches and pounds.
Enter height and weight
Both fields update the result as you type.
Read the category and healthy range
The panel shows your BMI, its category, and the weight range that would put you in the healthy band.
Worked examples
An adult who is 175 cm and 72 kg
- Inputs
- 175 cm · 72 kg
- Result
- BMI 23.5 — healthy weight