BMI Calculator
Body mass index, metric or imperial.
- 100% free
- No sign-up
- Runs in your browser
A quick health screening number
BMI compares weight to height. It's a simple screening measure used by doctors worldwide, with standard categories from underweight to obesity.
It doesn't distinguish muscle from fat or account for age and ethnicity, so treat it as a starting point rather than a diagnosis.
- 1
Choose units
Metric or imperial.
- 2
Enter height & weight
Results update instantly.
- 3
Read your category
And your healthy range.
Frequently asked questions
What is a healthy BMI?
18.5 to 24.9 for most adults, according to the WHO.
Is BMI accurate for athletes?
Not really — muscle is dense, so muscular people can show as overweight while being very fit.
Is my data uploaded anywhere?
No. Everything runs in your browser with JavaScript — nothing you type or open is sent to our servers.