BMI Calculator
Calculate body mass index from height and weight. Switch between metric (kg, cm), US customary (lb, ft/in), or other units — values convert internally before BMI is computed. BMI is a screening estimate, not a full health diagnosis.
How it works
- 1
Choose metric, US, or other units at the top of the form.
- 2
Enter height and weight — results update as you type.
- 3
Use Reset to try another scenario.
Why use this calculator
- Instant BMI value and category
- Multiple unit systems (metric, US, other)
- Healthy weight range for your height
- Private in-browser math
What BMI measures
BMI relates weight to height using the standard formula (weight ÷ height²). FlyCalculator accepts metric or US inputs and converts them internally, then maps the result to common adult categories.
Limitations
BMI does not measure body fat directly and may misclassify athletes or some body types. Use it as one screening signal among many, not a diagnosis.
Frequently asked questions
Is BMI a diagnosis?
No. It is a screening metric. Talk to a clinician for personal health advice.
Which units can I use?
Metric (kilograms and centimeters), US customary (pounds and feet/inches), or other units via the Other Units option, which links to the unit conversion calculator. All inputs are converted before BMI is calculated.
What are the categories?
Common adult bands: underweight, normal, overweight, and obese.