MotionShine01 / Formula
Weight over height squared
BMI is weight in kilograms divided by height in metres squared. US units are converted first.
Free tool
BMI calculator, for adults.
Type your height and weight in metric or US units to see your body mass index, where it sits on the scale, and the adult category as the US Centers for Disease Control and Prevention lists it. You also see the weight range that gives a BMI of 18.5 to under 25 for your height. BMI is a screening measure for adults 20 and older; it does not diagnose anything, and a doctor looks at much more.
Adult categories (CDC, read 17 Oct 2026): under 18.5 underweight; 18.5 to under 25 healthy weight; 25 to under 30 overweight; 30 or more obesity (class 1: 30 to under 35, class 2: 35 to under 40, class 3: 40 or more). For people 20 and older; children and teens use age and sex percentiles instead.
Worked out in your browser. Nothing is sent anywhere.
What BMI is
A quick screen, not a diagnosis.
02 / Categories
As the CDC lists them
The adult ranges on this page are the ones on the CDC's adult BMI page, read on 17 October 2026.
03 / Limits
Only part of the picture
BMI does not tell muscle from fat or show where fat is. The CDC calls it a screening measure.
Questions
Good to know.
How is BMI calculated?
Weight in kilograms divided by height in metres squared. 72 kg at 1.75 m is 72 รท 3.0625 = 23.5.
What is a healthy BMI for adults?
The CDC lists 18.5 to less than 25 as healthy weight for adults 20 and older.
Is BMI accurate for athletes?
Not always. Muscle weighs more than fat, so a muscular person can have a high BMI.
Can I use it for a child?
No. Children and teens use BMI-for-age percentiles, which this page does not show.
Is this medical advice?
No. Talk to a doctor about your health.