Body Mass Index Calculator

U.S. or Metric Units

Body Mass Index, or BMI, is commonly used to determine whether or not a person is at a healthy weight. A BMI of 18.5 to 24.9 is considered healthy; 25 to 29.9 represents overweight, while a person with a BMI of 30 or greater is said to be obese. These figures are said to be reliable in most cases, except for the following:

Though BMI is still widely used in doctor’s offices (mainly because it’s easy to measure and calculate), it is no longer considered to be the most accurate way to determine whether a person is normal, overweight, or obese, or even whether a person is healthy. People with high BMIs may have low body fat, or vice versa. Waist measurement (less than 35 inches for women, or 40 inches for men) or waist-to-hip ratio are cited as more accurate alternatives. The latter is determined by dividing the waist measurement (at the navel) by the hip measurement (at the buttocks). A ratio greater than 0.85 for women, or 0.9 for men, indicates too much belly fat. For more information, see the following articles:

BMI is calculated by dividing the person’s weight in kilograms by the square of his or her height in meters. For U.S. units, multiply the weight in pounds by 703.08, then divide by the square of the height in inches. For those not mathematically inclined, these online calculators will prove useful. They should not, however, substitute for the advice of a qualified health professional.

Calculate Body Mass Index from U.S. units

Useful height range is 4 to 8 feet.


Calculate Body Mass Index from metric units

Useful height range is 122 to 243 centimeters.