Body Mass Index Calculator

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:

• Growing children.
• Elderly people, whose BMI will likely be low due to decreased muscle mass.
• Serious athletes and body builders, whose BMI will likely be high due to increased muscle mass.
• Pregnant or lactating women, whose BMI will likely be higher than normal.

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:

• When determining who’s fat, is BMI bunk? (May 1, 2007)
• Top 10 Reasons Why The BMI Is Bogus (July 4, 2009)
• BMI Is A Terrible Measure Of Health (February 25, 2016)

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.