Ideal Weight Calculator - 4 Medical Formulas

Ideal Weight Calculator

This calculator averages four ideal body weight formulas, Devine, Robinson, Miller, and Hamwi, to estimate a target weight in kilograms or pounds from your height and sex. It also reports a healthy weight range built from a body mass index of 18.5 to 25.0, giving a second reference alongside the four-formula average. Both metric and imperial height input are supported, with separate coefficients for men and women in every formula.

How the calculation works

All four formulas take the number of inches a person's height is over five feet and add that to a fixed base weight, so the base differs by formula and so does the added weight per inch, the slope. Robinson (1983) and Miller (1983) both come from clinical dosing research that needed a fast weight estimate; Devine (1974) was built for the same purpose and remains the most cited version in medical literature; Hamwi (1964) is the oldest of the four and produces the widest per-inch increase for men. None of the four use age, so the calculator has no age field, only height and sex.

Men:   Devine 50.0 + 2.3 x in | Robinson 52 + 1.9 x in | Miller 56.2 + 1.41 x in | Hamwi 48 + 2.7 x in
Women: Devine 45.5 + 2.3 x in | Robinson 49 + 1.7 x in | Miller 53.1 + 1.36 x in | Hamwi 45.5 + 2.2 x in
in = height in inches minus 60 (result in kilograms)

Worked example

Take a man who is 5 feet 9 inches (175 cm) tall, 9 inches over the five-foot mark. Devine gives 50.0 + 2.3 x 9 = 70.7 kg, Robinson gives 52 + 1.9 x 9 = 69.1 kg, Miller gives 56.2 + 1.41 x 9 = 68.9 kg, and Hamwi gives 48 + 2.7 x 9 = 72.3 kg. The average of the four, 70.2 kg (154.9 lb), is the headline result, and the calculator also reports a BMI-based range of about 56.8 to 76.8 kg (125.3 to 169.3 lb) for the same height.

Healthy BMI range

The second figure the calculator reports uses the World Health Organization's body mass index bands: it takes the weight that produces a BMI of 18.5 at the low end and 25.0 at the high end, for the same height entered. The table below shows the four WHO categories that this range sits between.

These are population averages from four decades-old formulas and a WHO classification, not a diagnosis. Muscle mass, bone density, pregnancy, and age can all shift a healthy weight outside these numbers, so a doctor or registered dietitian is the right source for guidance specific to you.