BMI Calculator
Free BMI calculator: your body mass index and WHO weight category from height and weight, metric or imperial — instantly, in your browser.
updated
- ✓ Runs in your browser — nothing uploaded
- ✓ No sign-up
- ✓ Free, no limits
Adults only — BMI can't tell muscle from fat and isn't valid in pregnancy. A screening estimate, not medical advice.
This BMI calculator turns your height and weight into your body mass index and the World Health Organization category it falls in — underweight below 18.5, normal from 18.5 to 24.9, overweight from 25 to 29.9, and obese from 30. Enter your numbers in metric or imperial and the result updates instantly, along with the weight range that would put you in the normal band for your height.
The formula is the standard one used by clinicians worldwide: weight in kilograms divided by height in metres squared. Worked example: 70 kg at 175 cm is 70 ÷ 1.75² = 22.9 — normal weight. Everything is computed in your browser; your measurements are never uploaded.
BMI is a screening number, not a diagnosis. It cannot tell muscle from fat, so athletes often read overweight while carrying little fat, and it applies to adults, not children or pregnancy. Use it as a starting point alongside the body-fat and calorie tools, and talk to a clinician about what your number means for you.
Frequently asked questions
How is BMI calculated?
Weight in kilograms divided by height in metres squared. 70 kg at 1.75 m is 70 ÷ 3.06 = 22.9. In imperial the same formula is applied after converting, which is what this calculator does for you.
What is a healthy BMI?
The WHO adult bands are: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. The calculator also shows the weight range that corresponds to the normal band at your height.
Is BMI accurate for athletes or during pregnancy?
No. BMI cannot distinguish muscle from fat, so muscular people often score overweight while lean; and it is not valid during pregnancy or for children (they use age-specific charts). It is a population screening tool, not a medical verdict.
Is my data uploaded?
No. The arithmetic runs entirely in your browser — your height and weight are never sent anywhere.