BMI Calculator

The BMI Calculator computes your Body Mass Index from height and weight, in either metric (kilograms and centimeters) or imperial (pounds, feet and inches) units, and instantly shows where the result falls on the standard World Health Organization scale: underweight, healthy weight, overweight or obese. It's meant for anyone who wants a quick, private read on how their weight relates to their height — a general health check-in, tracking progress over time, or filling out a form that asks for body mass index.

The formula is straightforward: BMI = weight in kilograms divided by height in meters squared (or, for imperial units, 703 × weight in pounds divided by height in inches squared). A result under 18.5 is classified as underweight, 18.5–24.9 as healthy weight, 25–29.9 as overweight, and 30 and above as obese — the same thresholds used by most doctors' offices and health apps. Switch between metric and imperial at any time; the calculator converts and recalculates instantly.

BMI is a fast screening measure, not a diagnosis, and it has real limitations. It doesn't distinguish muscle from fat, so a muscular athlete can score 'overweight' by BMI while carrying very little body fat, and it doesn't account for bone density, waist-to-hip ratio, or where fat is distributed on the body. Use it as a starting point for a conversation about a healthy weight, not a final verdict — waist circumference and body-fat percentage give a fuller picture, and a healthcare professional can put your number in context.

Every measurement is processed locally in your browser using JavaScript; nothing is uploaded, logged or stored on a server, so you can check your BMI as often as you like with complete privacy. Because the calculation takes only two numbers, it's also a convenient way to see how a target weight would change your BMI category before setting a goal.