CalcKitHow to Use the BMI Calculator
Body Mass Index (BMI) is the world's most widely used screening measure for weight categories. It is calculated by dividing your weight in kilograms by the square of your height in metres. Doctors, fitness coaches and insurance companies all use it as a quick first check of whether someone's weight is in a healthy range for their height.
To use this calculator, pick your preferred units (metric or imperial), enter your height and weight, then press Calculate BMI. You will instantly see your BMI value, your weight category โ underweight, normal, overweight or obese โ and the healthy weight range for your height, so you know roughly what target to aim for.
The standard adult categories are: below 18.5 is underweight, 18.5 to 24.9 is the normal healthy range, 25 to 29.9 is overweight, and 30 or above is obese. These cut-offs come from the World Health Organization and are the same ones your doctor uses.
Keep in mind that BMI is a screening tool, not a diagnosis. Very muscular people, athletes and pregnant women can get misleading results because BMI cannot tell muscle apart from fat. If your result surprises you, treat it as a prompt to talk to a health professional rather than a final verdict โ and pair it with our Calorie Calculator to plan a sensible diet.