BMI Calculator — Free Online Tool

The BMI Calculator divides your weight by the square of your height (kg/m², or the equivalent imperial formula using pounds and inches) to produce a single Body Mass Index number, then places that number into the standard WHO categories: underweight, normal weight, overweight, and obese. Both metric (kg/cm) and imperial (lbs/ft-in) input are supported, so you don't need to convert units before calculating.

BMI is a population-level screening measure, not a diagnosis — it was designed to flag trends across large groups, not to assess an individual's health precisely. It doesn't distinguish muscle mass from fat mass, which is why a muscular athlete can show a BMI in the 'overweight' range while carrying very little body fat, and it doesn't account for age, sex-specific body composition differences, or where fat is distributed on the body, all of which affect actual health risk more than the raw number does.

Despite those limits, BMI remains useful as a quick, standardized starting point — many clinical guidelines still use BMI thresholds as a first screening step before more detailed assessment. If your result falls outside the 'normal' range, or you have specific health concerns, that's a conversation for a doctor who can factor in the context BMI leaves out, not a conclusion to draw from this number alone.

Everything calculates instantly in your browser from the numbers you enter — nothing about your height, weight, or resulting BMI is sent anywhere or stored.

Our BMI Calculator is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.

Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.