BMI Calculator

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, obesity) that may be linked to health problems. But BMI doesn’t directly measure a person’s health. The BMI should be used along with other measures, including your level of physical activity, blood pressure and cholesterol levels, to assess your risks for disease.

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 obesity categories.

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.

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

That depends. BMI 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 are based primarily on white populations, so it may be less accurate for people of other races and ethnicities.

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.

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.