BMI Calculator

Clinics and forms ask for body mass index as a single number from weight and height. BMI Calculator uses kilograms and centimeters and names an adult category.

The formula on this page

Weight is divided by height in meters squared. Centimeters are divided by 100 to get meters, so 180 cm is 1.8 m. A result under 18.5 is labeled Underweight, from 18.5 up to but not including 25 is Normal, from 25 up to but not including 30 is Overweight, and 30 or more is Obesity. Those cutoffs are the common adult bands. The page does not adjust them for children, athletes, pregnancy, or older adults. Both fields must be greater than zero. The number is rounded to one decimal in the result line.

What the label is not

BMI is a screening ratio, not a diagnosis and not a body-fat percentage. Two people with the same index can have different muscle and fat. This page does not ask for age, sex, waist, or activity, so it cannot estimate calories. BMR Calculator uses Mifflin–St Jeor when you want a calorie baseline and does ask for those inputs. Calorie Deficit Calculator starts from a daily energy number. Macro Calculator splits grams of protein, fat, and carbohydrate. Ideal Weight Calculator is a separate estimate, not a rewrite of this index.

What this tool will not do

It will not convert pounds or inches. Type kilograms and centimeters, or convert before you calculate. It will not store a history, chart a trend, or give medical advice. The category names are fixed bands, not a personalized range. Weight and height stay in this browser tab. If the form you are filling uses imperial units, convert first so you do not enter pounds into the kilogram field.