BMI Calculator (Metric & Imperial)
Calculate your Body Mass Index from height and weight and see your BMI category.
Quick answer: BMI = weight (kg) ÷ height (m)². A BMI of 18.5–24.9 is considered a healthy weight for most adults.
Worked example
A person who weighs 70 kg and is 170 cm tall has a BMI of 70 ÷ (1.70 × 1.70) = 24.2, which sits in the healthy range. At 154 lb and 67 in the result is 24.1, because the calculator converts pounds and inches for you.
How to use it
- Choose metric (kg and cm) or imperial (lb and inches).
- Enter your weight and height.
- Read your BMI and the category shown under it.
Adult BMI categories (World Health Organization)
| BMI | Category |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25.0 to 29.9 | Overweight |
| 30.0 and above | Obese |
Common mistakes
- Treating BMI as a diagnosis. It is a screening number only.
- Using it for children and teenagers. They use age-based growth charts instead.
- Reading too much into it for very muscular people, who can score high without carrying extra fat.
Helpful tips
- Waist size and how you feel matter too. A doctor can look at the whole picture.
- This tool is for information only and is not medical advice.
Read the guide
Frequently asked questions
What is a healthy BMI?
For most adults a BMI between 18.5 and 24.9 is considered healthy.
Is BMI accurate?
BMI is a quick screening number. It does not measure body fat or muscle, so athletes and older adults may see misleading results.
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