Check your Body Mass Index in seconds. Our free BMI calculator takes your height and weight and instantly shows your BMI value plus your weight category — underweight, healthy, overweight, or obese — based on standard World Health Organization ranges.
BMI is a widely used screening measure: under 18.5 is underweight, 18.5-24.9 healthy, 25-29.9 overweight, 30+ obese. It is a general guide, not a medical diagnosis.
BMI is the quickest screening snapshot of weight-related health: doctors, insurers, and fitness programs all use it as a starting point. Knowing your number — and which category it falls into — helps you set realistic goals and track progress over time. Our calculator does the math instantly and color-codes your result, so your category is clear at a single glance.
Between 18.5 and 24.9 is considered the healthy range for most adults, according to the World Health Organization.
Not always — very muscular people can have a high BMI without excess body fat. BMI is a screening tool, not a diagnosis; athletes should also consider body-fat percentage and waist measurements.
The formula is the same for all adults, but interpretation differs for children, teenagers, and older adults. This calculator is designed for adult use.
If your BMI falls outside the healthy range, it's worth discussing with a healthcare professional, who can assess your overall health far beyond this single number.