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BMI Calculator
Your Body Mass Index from height and weight, with the usual category bands. Informational only.
Your BMI
BMI is a rough population guide. It does not measure body fat, and it is not a diagnosis. If you are concerned, speak to a clinician.
How it works
BMI = weight in kg ÷ (height in metres)²
Worked example: 70 kg at 170 cm. Height in metres is 1.70, squared is 2.89, and 70 ÷ 2.89 = 24.22 — in the healthy band of 18.5 to 24.9.
Frequently asked questions
What do the BMI bands mean?
Below 18.5 is underweight, 18.5–24.9 is healthy, 25–29.9 is overweight, and 30 or above is obese. These are population bands, not a personal diagnosis.
Is BMI a complete health measure?
No. It does not distinguish muscle from fat, and it does not account for age, sex or body shape. Use it as a rough guide only.
Why does height need to be in metres?
The formula divides by height squared in metres. At 170 cm that is 1.70 m, and 1.70 × 1.70 = 2.89.
Should I act on this result?
Talk to a clinician before changing diet or exercise on the basis of a BMI number. This tool is informational only and is not medical advice.