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BMI Calculator

Your BMI — a ratio of your weight to your height — helps to determine if you are at a healthy weight

Calculate Your Body Mass Index

Your BMI can tell you whether you’re carrying too much, too little or just the right amount of body fat.

Free BMI calculator for adults

En español | Your body mass index (BMI) is an estimate of your body fat that is based on your height and weight. Doctors use BMI, along with other health indicators, to assess an adult’s current health status and potential health risks. People with higher BMIs are more likely to develop chronic conditions such as type 2 diabetes, sleep apnea and heart disease. To determine your own BMI, use this calculator.

To calculate your BMI, select your height and weight below. When you click the ‘Calculate’ button, you’ll be taken to a section about your results.

Free BMI calculator for adults

(NOTE: BMI should not be used to assess a child’s weight because the appropriate weight for a child varies greatly by age.)

Typically, people with higher BMIs have a greater likelihood of developing conditions such as heart disease, high blood pressure, sleep apnea, and type 2 diabetes. But many factors — including your family history, eating habits and activity level — also influence your overall health.

BMI calculator results are grouped into the broad categories of underweight, healthy weight, overweight and obese.

As you review your results keep in mind that BMI has its limits, and that BMI recommendations do differ based on gender and other variables. (For instance, BMI may underestimate body fat in an older person who has lost muscle tone.)

If you have questions or concerns about your BMI results, consult with your doctor or health care provider.


What is BMI?

BMI, or body mass index, is a screening tool that takes into account a person’s height and weight. It slots people into four weight groups (underweight, healthy weight, overweight, obese) that may be linked to health problems. But BMI doesn’t directly measure a person’s health.

What is a healthy BMI?

The healthy weight category is defined as a BMI of between 18.5 and 24.9. A weight in this category is linked to fewer health problems than the underweight, overweight and obese categories.

What should my BMI be?

The “healthy weight” category—defined as a BMI of between 18.5 to 24.9—is considered ideal. But keep in mind that BMI is not a perfect measure. For example, it does not take into account how much fat you carry or where the fat is distributed, factors that can affect your metabolic health.

How is BMI calculated?

Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters.

How accurate is BMI?

That depends. BMI also can’t tell how much of your weight is from fat or muscle, so it misses information important to assessing your health risks.For instance, athletes can have a high BMI because of their muscle mass, even if they’re not overweight. Also, the definitions for the weight categories were based primarily on white populations, so it may be less accurate for people of other races and ethnicities.

How can age or race affect BMI?

BMI doesn’t differentiate between fat, bone and muscle; therefore, it may be less accurate for older people, who tend to lose muscle mass and bone density as they age. (That’s why people over 65 may benefit from a slightly higher BMI, between 25 and 27.) Research shows that the BMI definition of obesity overestimates risk in Black people and underestimates it in individuals of Asian descent, which may lead to inappropriate treatment and health disparities.

Are BMI recommendations the same for men and women?

The recommended amount of body fat differs for men and women. For women, the ideal body fat is 20 to 21 percent. (The average American woman has about 22 to 25 percent body fat.) For men, the recommended amount of body fat is between 13 and 17 percent. (The average American man has about 17 to 19 percent body fat.) 

To determine your ideal body weight, try this formula:

  • Women: 100 pounds of body weight for the first 5 feet of height + 5 pounds for each additional inch.
  • Men: 106 pounds of body weight for the first 5 feet of height + 6 pounds for each additional inch.

If you have a small body frame, however, subtract 10 percent from that number. For a large frame, add 10 percent.