BMI Calculator
Check your Body Mass Index in seconds — with metric or imperial units, and an instant weight-category result.
What your BMI tells you
Body Mass Index distills the relationship between your height and weight into a single number. Doctors and insurers use it as a quick first screen: a BMI between 18.5 and 24.9 is generally considered healthy for adults, 25–29.9 signals overweight, 30+ signals obesity, and below 18.5 signals underweight. It takes ten seconds and a tape measure — no lab visit required.
That simplicity is also its limit. BMI cannot distinguish a pound of muscle from a pound of fat, so athletes, bodybuilders, pregnant women, and older adults with reduced muscle mass can land in misleading categories. Use this free BMI calculator — with one-tap switching between metric and imperial units — as a starting point for a conversation with your doctor, not as a verdict on your health.
How to use the BMI calculator
- Pick your units: metric (cm/kg) or imperial (ft, in/lb).
- Enter height and weight: the result updates live as you type.
- Read your category: the color-coded badge shows where you land on the standard scale.
Frequently asked questions
What is BMI?
Body Mass Index relates your weight to your height: weight in kilograms divided by height in meters squared. It places you in one of four categories — underweight, normal, overweight, or obese.
What is a healthy BMI range?
For most adults, 18.5 to 24.9 is the healthy range. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate for everyone?
Not always. BMI can't distinguish muscle from fat, so very muscular people, pregnant women, and older adults with low muscle mass can get misleading results. Treat it as a rough screening tool, not a diagnosis.
Is my height and weight data private?
Yes. The calculation happens entirely in your browser — your measurements are never uploaded, stored, or shared.