BMI Calculator
Calculate your Body Mass Index from height and weight, in metric or imperial units.
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Body mass index
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Enter your height and weight.
How it works
BMI (Body Mass Index) estimates body fat from height and weight with one formula:
In imperial units the math is equivalent: 703 × weight (lb) ÷ height (in)². The standard adult categories, used by the CDC and WHO, are:
- Below 18.5 — Underweight
- 18.5 to 24.9 — Healthy weight
- 25 to 29.9 — Overweight
- 30 and above — Obesity
Frequently asked questions
What is a healthy BMI range?
According to the CDC and WHO, a BMI between 18.5 and 24.9 is considered the healthy weight range for most adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is in the obesity range.
How is BMI calculated?
BMI is your weight in kilograms divided by your height in meters squared (kg/m²). In imperial units the equivalent formula is 703 × weight in pounds divided by height in inches squared.
Is BMI accurate for everyone?
Not always. BMI does not distinguish muscle from fat, so athletes can score high while being lean. It is also less reliable for children, older adults, and during pregnancy. Think of it as a screening starting point, not a diagnosis.
Should I see a doctor about my BMI?
BMI alone cannot tell you whether you are healthy. If your result is outside the healthy range, or you have concerns about your weight, talk to a healthcare professional who can look at the full picture.