BMI Calculator
Calculate your Body Mass Index and find out your weight category.
Your BMI
Unit Converter
Quickly convert between metric and imperial units.
Weight
Height
BMI Calculator — Your Number, Explained
Body Mass Index is the standard quick screen for weight categories: underweight, normal, overweight and obese. Enter your height and weight in metric or imperial units and this free BMI calculator shows your exact BMI, places you on a color-coded scale, and estimates your healthy weight range.
You also get the weight you would need to lose or gain to reach the healthy range, plus BMI Prime — your BMI divided by 25. Everything computes instantly in your browser; no data is stored or uploaded.
Metric and imperial units
Switch between centimeters/kilograms and feet/inches/pounds with one toggle. The calculator converts units correctly so your result is the same either way.
More than just a number
See your healthy weight range, how far you are from it, and your BMI Prime — context that turns a raw number into something you can act on.
A screening tool, not a diagnosis
BMI does not distinguish muscle from fat and can misclassify athletes, pregnant people and older adults. Treat your result as a starting point and talk to a healthcare professional about what it means for you.
How to use
- Choose Metric or Imperial units.
- Enter your height and weight.
- Click Calculate BMI.
- Review your category, healthy range and BMI Prime on the scale.
Frequently Asked Questions
How is BMI calculated?
BMI equals weight in kilograms divided by height in meters squared. In imperial units it is 703 times weight in pounds divided by height in inches squared.
What are the BMI categories?
Under 18.5 is underweight, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight, and 30 or above is obese.
What is BMI Prime?
BMI Prime is your BMI divided by 25, the upper limit of the healthy range. A value of 1.0 means you are exactly at that boundary; below 1.0 is inside the healthy range.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so very muscular people can land in the overweight range while being perfectly healthy. BMI is a population screening tool, not a body-composition test.
Is my height and weight data stored?
No. The calculation runs entirely in your browser and nothing you enter is uploaded or saved.
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