Calculate your body mass index using either metric or imperial units, and see instantly which weight category your BMI falls into.
How This BMI Calculator Works
Choose metric or imperial units at the top, enter your weight and height, then click "Calculate BMI." Your body mass index is calculated instantly along with the weight category it falls into: underweight, normal weight, overweight, or obese. Switch units at any time and recalculate without losing your place.
Understanding BMI Categories
- Underweight. A BMI below 18.5.
- Normal weight. A BMI from 18.5 to 24.9.
- Overweight. A BMI from 25 to 29.9.
- Obese. A BMI of 30 or higher.
BMI is a simple screening measure based only on height and weight. It does not account for muscle mass, bone density, body composition, age, or sex, so it should be treated as a general starting point rather than a precise diagnosis of health.
Who This Tool Is For
Anyone tracking their weight relative to a general health guideline, people comparing metric and imperial measurements, and anyone curious about where their BMI falls before discussing it further with a healthcare provider.
Frequently Asked Questions
Is this calculator free to use?
Yes, completely free with no limit on how many times you can use it, and no account is required.
Is BMI an accurate measure of health?
BMI is a useful general screening tool, but it does not distinguish between muscle and fat, so athletes and very muscular people can show a higher BMI without carrying excess fat. It should not replace a full evaluation from a healthcare provider.
Does this tool send my weight or height to a server?
No. The calculation happens entirely in your browser using JavaScript. Your numbers are never uploaded or saved anywhere.
Can I switch between metric and imperial units?
Yes. Click either tab at the top to switch units at any time, and enter your measurements in whichever system you prefer.