BMI Calculator
Find your body mass index from your height and weight, using US units first — pounds, feet and inches.
| Category (CDC, adults) |
BMI is a screening measure, not a medical diagnosis. Talk to your doctor for personal advice.
What is this tool?
Body mass index (BMI) is a quick screening number that compares your weight with your height. Doctors, insurers and fitness programs across the United States use it as a first check of whether an adult's weight falls in a healthy range. This BMI calculator defaults to the units Americans actually use — pounds, feet and inches — with a metric toggle if you prefer kilograms and centimeters.
BMI is a screening tool, not a diagnosis. It does not measure body fat directly, and it can mislead for muscular athletes (who may score high with low body fat) and for older adults (who may score normal while carrying too much fat). Treat the result as a starting point for a conversation with your doctor, not the final word on your health.
How to use it
- Enter your weight in pounds and your height in feet and inches (or switch to metric).
- Click Calculate.
- Read your BMI and the CDC adult category it falls into.
Formula & method
Worked example
An adult who weighs 180 lb and stands 5 feet 10 inches (70 inches) tall has a BMI of 703 × 180 ÷ 70² ≈ 25.8, which lands in the overweight range. Dropping to about 174 lb would bring the same person just under 25, the top of the healthy range.
Frequently asked questions
What is a healthy BMI for adults?
For adults 20 and older, the CDC defines a healthy BMI as 18.5 to 24.9. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or higher is obesity.
Is BMI accurate for athletes?
Often not. Muscle weighs more than fat, so a lean, muscular athlete can have a BMI in the overweight or obesity range despite low body fat. Waist measurement and body composition tests give a fuller picture.
Does BMI work the same for children and teens?
No. For ages 2 to 19, BMI is interpreted using CDC growth-chart percentiles that account for age and sex, not the adult cutoffs shown here.