ideal weight : About arithmetic formulas for calculating ideal body weight

The history of the formulas for calculating ideal body weight began in 1871 when Dr. P.P. Broca4 (a French surgeon) created this formula ( known as Broca's index):

Weight (in kg) should equal Height( in cm) - 100, plus or minus 15% for women or 10% for men.

An unknown person translated Broca's formula into pounds and inches, and modified it to create this improved simple rule:

"For women, allow 100 lbs for the first 5 feet and 5lbs for each additional inch. For men, allow 110 lbs for the first 5 feet and 5 lbs for each additional inch"1.

These formulas pre-dated and probably influenced development of the Metropolitan Life tables of height and weight. As discussed on another page, the Met Life tables were created in 1943, and were commonly used by the 1970s as a surrogate indicator of desirable or "ideal" body weight. Thus, the Met life tables strongly influenced the subsequent development of other formulas.

Dr. BJ Devine published the following formula in 1974, which basically converted the above simple rule from pounds to kilograms, for medical use:

men: Ideal Body Weight (in kilograms) = 50 + 2.3 kg per inch over 5 feet.
women: Ideal Body Weight (in kilograms) = 45.5 + 2.3 kg per inch over 5 feet.

This "Devine formula" was intended to be used to calculate the dosage of certain medications such as gentamicin, digoxin and theophylline. But after its publication, the formula became much more widely used.. In fact, the Devine formula is the most commonly used formula on the internet for ideal body weight. It appears on MANY HUNDREDS of javascript calculator pages!

Later in 1983, Dr. JD Robinson discovered through correpondence with Dr. Devine, that the Devine equations were not based on any defined population data. Instead, they were apparently based on estimates from Dr. M. McCarron, who was Dr. Devine's mentor1.

Now, in modern times, we can examine the Devine formulas more scientifically, and compare them to current knowledge. The following charts show the Devine formula compared to the average weight2 and lean body mass3 of the American population.

The "Lean Body Weight" refers to the weight of all of the body's organs, bone and muscles, WITHOUT FAT. As you can see, the women's formula gets too close to the Lean Body Weight, in short women.

The Devine formula suggests an ideal weight, which would create an average Body Mass Index of 23.0 kg/m2 in the adult Male population, (which is appropriate), but for women, it suggests an ideal weight that would create an average Body Mass Index of 20.8 kg/m2 in the adult Female population, which is too low.

In 1983, Dr. JD Robinson published a modification of the formula5, and Dr. DR Miller published a different modification.

Robinson: Men: Ideal Body Weight (in kilograms) = 52 kg + 1.9 kg for each inch over 5 feet

Women: Ideal Body Weight (in kilograms) = 49 kg + 1.7 kg for each inch over 5 feet


Miller Men: Ideal Body Weight (in kilgrams) = 56.2 kg + 1.41 kg for each inch over 5 feet

Women: Ideal Body Weight (in kilograms) = 53.1 kg + 1.36 kg for each inch over 5 feet.

by Steven B. Halls, MD. Copyright