BMI Calculator

Calculate your body mass index and see your healthy weight range, using CDC adult categories.

By the CalculateBright team · Updated · How we calculate

Units
  

    How to use the BMI calculator

    1. Enter your numbers. Fill in units, height, height, weight.
    2. Read your results. Results update instantly. The headline shows the your bmi; the breakdown and table below show the details.

    What is BMI?

    Body mass index is weight relative to height. The CDC uses it as an inexpensive screening measure for adults 20 and older. It isn’t a diagnosis: it doesn’t measure body fat directly or account for muscle, age, sex or ethnicity.

    The formula

    BMI = 703 × weight (lb) ÷ height (in)²
    BMI = weight (kg) ÷ height (m)²

    Adult BMI categories

    Below 18.5 is underweight, 18.5–24.9 healthy weight, 25–29.9 overweight and 30 or above obesity. For children and teens, BMI is interpreted with age- and sex-specific percentiles instead.

    Worked example

    With these inputs: unitsUS (lb, ft); height (ft)5; height (in)10; weight (lb)175.

    The calculator gives a your bmi of 25.1 (overweight). Other results: categoryOverweight, healthy weight range129 lb – 174 lb, healthy bmi range18.5 – 24.9, to reach bmi 24.9lose 1 lb.

    What your results mean

    BMI is a screening measure that compares weight to height. CDC adult categories: underweight below 18.5, healthy 18.5–24.9, overweight 25–29.9 and obesity 30 or above. It does not measure body fat directly and can misclassify very muscular people.

    Tips

    • Use BMI alongside waist size and other health markers.
    • Children and teens need age- and sex-specific BMI percentiles, not adult categories.
    • Talk to a healthcare provider about what a healthy weight means for you.

    Frequently asked questions

    What is a healthy BMI?

    For adults, the CDC classifies 18.5 to 24.9 as a healthy weight range.

    Is BMI accurate for athletes?

    Not always. Muscle weighs more than fat, so muscular people can have a high BMI without excess body fat. A body fat estimate can add context.

    Is BMI accurate for athletes?

    Not always. Muscular people can have a high BMI with low body fat. Try the body fat calculator.

    Does BMI apply to children?

    Not with these categories. Children use BMI-for-age percentiles from the CDC.

    What should I do if my BMI is high?

    Talk with a healthcare provider, who can consider other measures like waist size, blood pressure and blood tests.

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    Sources