BMI calculator
This free BMI (body mass index) calculator gauges the ratio of your weight to your height and shows which category the result falls into. Enter your weight (kg) and height (cm) and you'll immediately see the index, the category (underweight, normal, overweight, obesity class I–III) and the healthy weight range for your height. Decimals can be typed with a comma (70,5 kg) and height in metres works too (1,75).
How the calculation works
The BMI formula is weight (kg) / height² (in metres). To convert height to metres, divide centimetres by 100. WHO classification: below 18.5 is underweight, 18.5–24.9 is normal, 25–29.9 is overweight, 30–34.9 is obesity class I, 35–39.9 class II, 40 and above class III. The healthy weight range is height² × 18.5 … 24.9. BMI is a general indicator and doesn't account for muscle mass.
Worked example
For 70 kg and 175 cm, BMI = 70 / (1.75)² ≈ 22.9 — normal. At the same weight with 160 cm you'd get ~27.3 — overweight.
Frequently asked questions
What BMI is normal?
A value between 18.5 and 24.9 is considered normal.
Is BMI accurate?
It's a general indicator and ignores muscle, age and sex. Consult a doctor.
What units are used?
Weight in kilograms (kg), height in centimetres (cm).
Is the tool free?
Yes — completely free.
Are BMI norms different in Georgia, Azerbaijan or Armenia?
No. Doctors in all three countries use the WHO adult classification: overweight from 25, obesity from 30.
What should I weigh for my height?
The calculator shows the weight that matches a BMI of 18.5–24.9. For example, at 170 cm that's roughly 53.5–72 kg.
How is BMI calculated for children?
For ages 5–19 WHO uses BMI-for-age (percentiles); this calculator is for adults aged 18+. For a child, ask a paediatrician.