BMI Calculator
Body mass index with healthy weight range.
< 18.5 Underweight 18.5โ24.9 Normal โ 25โ29.9 Overweight 30โ34.9 Obesity I 35โ39.9 Obesity II โฅ 40 Obesity III
BMI is a rough screening tool โ it does not account for muscle mass, age or body composition.
About the BMI Calculator
Calculate body mass index from metric or imperial measurements, with the result placed on the standard WHO scale from underweight through obesity class III. The tool also converts your BMI back into a personal healthy weight range, showing the kilograms or pounds that correspond to a BMI of 18.5 to 24.9 for your height.
How to use the BMI Calculator
- Choose the Metric (cm, kg) or Imperial (ft/in, lb) tab.
- Enter your height and weight in the fields shown.
- Read your BMI value and its color-coded category.
- Check the Healthy weight range for your height, and the full BMI scale table below.
BMI Calculator FAQ
How is BMI calculated?
Metric uses weight in kilograms divided by height in meters squared; imperial multiplies pounds divided by inches squared by 703 โ both produce the same index.
What are the category cutoffs?
Below 18.5 is underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, and 30 and above splits into obesity classes I, II and III.
Is BMI accurate for athletes?
It is a rough screening tool only โ BMI does not distinguish muscle from fat, so muscular people can score high despite low body fat, as the disclaimer in the tool notes.