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BMI Calculator

Enter your height and weight to calculate your body mass index and see which adult category it falls in. BMI is a screening number, not a diagnosis.

Your numbers

Result

Estimate for information only, not professional advice. Last reviewed .

How we calculate it

BMI = weight in kilograms ÷ (height in meters)². In US units, BMI = 703 × weight in pounds ÷ (height in inches)².

For adults, the CDC categories are: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25.0 to 29.9 overweight and 30.0 or higher obesity.

How to read your result

  • BMI is weight divided by height squared. Adults are usually grouped as under 18.5, 18.5 to 24.9, 25 to 29.9 and 30 or more.
  • The scale under the number shows where you fall between those groups.
  • It is a screening number, not a diagnosis: it does not know your muscle, bone or where you carry weight.
  • A result near a boundary is not a sharp line. A small change in weight can move you across it.

Common mistakes

  • Treating BMI as a measure of health. Athletes can score high, and older adults can score normal with low muscle.
  • Using the wrong units. Check that the setting matches the numbers you typed (pounds and inches, or kilograms and centimeters).
  • Using adult categories for children and teens. They use age and sex percentile charts instead.
  • Ignoring other measures such as waist size, blood pressure and cholesterol. Talk to a doctor about the full picture.

Assumptions and limits

  • BMI is a screening tool. It does not measure body fat, muscle, bone density or where fat is stored, and it can misclassify athletes and older adults.
  • These categories apply to adults aged 20 and over. For children and teens, BMI is interpreted by percentile for age and sex.
  • This is general information, not medical advice. Talk to a healthcare professional about your health.

Frequently asked questions

What is a healthy BMI?

For adults, the CDC defines a healthy weight as a BMI from 18.5 to 24.9.

Is BMI accurate?

It is a quick screen that works reasonably for populations but can be misleading for individuals, especially very muscular people. It is best combined with other measures and a clinician’s judgment.

What is the weight range for my height?

The calculator shows the weights that correspond to BMI 18.5 and 24.9 for your height.

Related calculators

Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Units = US (feet, inches, pounds); Height (feet) = 5; Height (inches) = 10; Weight (pounds) = 160.

  • BMI 23.0
  • Adult category (CDC) Healthy weight
  • Weight range for BMI 18.5–24.9 129–174 lb

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.