How to calculate your BMI?

What is BMI, or body mass index, and how does it measure health? Calculating BMI can help you discover if you have any weight-related health risks.

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What Is BMI?

BMI uses your height and weight to determine if you are at risk for conditions such as heart disease, high blood pressure, high cholesterol, and type 2 diabetes. The higher your BMI number, the greater your risk.

To calculate your risk of weight-related diseases, put your height, weight, and waist circumference into this online BMI and Health Risks calculator. It’s best to weigh yourself in the morning without clothes. Compare your results to the following numbers, which will show you whether you are underweight, a normal weight, overweight, or obese:

  • Underweight: Below 18.5
  • Normal range: 18.5-24.9
  • Overweight: 25-29.9
  • Obese: 30 or higher

If you’re overweight or obese, consult your doctor to determine your health risks. As the American Cancer Society notes, your doctor might consider other factors such as body fat, family history, diet, and fitness level to evaluate your health.

Being underweight can also be unhealthy. If you struggle to gain weight, ask your doctor about health conditions that might be preventing you from adding pounds.

How Good Is BMI at Indicating Body Fat?

BMI isn’t a perfect measure.

According to the Centers for Disease Control and Prevention,  the correlation between the BMI and body fatness is fairly strong. But two people can have the same BMI, yet their level of body fatness may differ because:

  • Women tend to have more body fat than men
  • Blacks have less body fat than Caucasians, and Asians have more body fat than Caucasians
  • Older people, on average, tend to have more body fat than younger adults
  • Athletes have less body fat than do nonathletes

BMI is a free, easy tool for you and your doctor to use to start measuring your health. But it’s just a starting point. If you don’t know your BMI, try calculating it with this handy online calculator. Then ask your doctor about other ways to measure your overall health.