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Free BMI Calculator

Calculate your Body Mass Index using metric (kg/cm) or imperial (lbs/ft-in) units — instantly, right in your browser.

kg
cm
lbs
ft
in
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Enter your details
Underweight
< 18.5
Normal
18.5–24.9
Overweight
25–29.9
Obese
30+
BMI is a general screening tool and does not account for muscle mass, bone density, or body composition. It is not a diagnosis. See our Disclaimer for more, and talk to a doctor about any health concerns.
About This Tool

What is BMI and
how is it calculated?

Body Mass Index (BMI) is a simple ratio of your weight to your height, used as a general screening tool to estimate whether your weight falls within a healthy range for your height. It's calculated the same way for adult men and women.

Metric formula: BMI = weight (kg) ÷ height (m)²

Imperial formula: BMI = (weight (lbs) ÷ height (in)²) × 703

For most adults, BMI results fall into one of four categories:

BMI is a useful general indicator, but it doesn't directly measure body fat. It can overestimate body fat in muscular people (like athletes), and may not fully reflect body composition in older adults who've lost muscle mass. It's best used alongside other health measures, not as a standalone diagnosis.

FAQ

Common questions.

BMI (Body Mass Index) is a simple ratio of your weight to your height, used as a general screening tool to estimate whether your weight falls within a healthy range for your height.

In metric units, BMI is calculated as weight in kilograms divided by height in meters squared (kg/m²). In imperial units, it's weight in pounds multiplied by 703, divided by height in inches squared.

For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range. Below 18.5 is categorized as underweight, 25 to 29.9 as overweight, and 30 or above as obesity.

BMI is a useful general screening tool, but it doesn't directly measure body fat and has known limitations. It can overestimate body fat in muscular people like athletes, and may underestimate it in older adults who have lost muscle mass.

No. For adults, BMI is calculated using the exact same formula and weight categories for both men and women. BMI calculation methods differ for children and teens, which take age and sex into account.

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