BMI Calculator
Calculate your Body Mass Index to understand whether your weight is in a healthy range for your height.
Your weight in kilograms
Your height in centimeters
BMI is a general indicator and does not account for muscle mass, bone density, or body composition.
Learn More About BMI Calculator
What BMI measures
BMI stands for Body Mass Index. It is a screening measurement that compares your weight to your height to estimate whether you are in a lower, typical, higher, or much higher weight range.
The standard metric formula is weight in kilograms divided by height in meters squared. For imperial units, the equivalent formula is weight in pounds divided by height in inches squared, multiplied by 703.
Example BMI calculation
If someone weighs 150 pounds and is 5 feet 7 inches tall, their BMI is about 23.5. That falls within the commonly used “normal weight” category for adults.
A BMI result becomes more useful when you look at the category and not just the number. Small changes in height or weight can shift the score, so it helps to interpret the result as a range rather than an exact health diagnosis.
When BMI is less reliable
BMI does not separate fat from muscle, so very muscular people may get a high BMI despite having low body fat. It also does not reflect age-related body composition changes or differences between populations.
Use BMI as a quick screening tool, not a final answer. Waist circumference, fitness level, blood pressure, and guidance from a healthcare professional can give a more complete picture.
Sources and references
The BMI formula and adult category ranges on this page follow public CDC guidance. BMI is a screening tool rather than a diagnosis, which is why the page also calls out situations where BMI can be less informative on its own.
Frequently Asked Questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is a measure of body fat based on height and weight. It is calculated by dividing your weight in kilograms by the square of your height in meters. For imperial units, the formula is: (weight in lbs / height in inches²) × 703.
What do my BMI results mean?
BMI categories are: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30 or higher). These ranges apply to adults aged 20 and older and are the same for men and women.
Are BMI scores accurate for everyone?
No. BMI does not distinguish between muscle and fat, so athletes and muscular individuals may score high despite low body fat. It also does not account for age, gender, or ethnicity — all of which affect body composition. Use BMI as a general screening tool, not a diagnostic measure.
Should I rely on BMI for my health decisions?
BMI is one of many health screening tools. It does not measure body fat directly or account for overall health. For a more complete picture, consider waist circumference, blood pressure, blood sugar, and cholesterol levels alongside BMI. Consult a healthcare provider for personal advice.