The formula
How it works
Ideal body weight is a rough target based on your height and sex. Several formulas exist and they disagree slightly, so this calculator shows the classic Devine result alongside three others and a healthy weight range from BMI.
FAQ
How accurate is ideal body weight?
It is only a guide. These formulas were built from population averages and ignore build, muscle and frame size, so a muscular person can be “over” their ideal weight yet perfectly healthy.
Which formula should I trust?
No single one is “correct”. The Devine formula is the most widely used, especially for medication dosing, but comparing all four and the BMI range gives a more honest sense of a healthy target.
Why do the formulas need a different value for men and women?
Men and women have different average frame sizes and body composition at the same height, so each formula uses a lower base weight and slope for women to better match population averages.
Does ideal weight change with age?
These formulas don’t adjust for age — they use only height and sex. Body composition naturally shifts as people get older, so an ideal weight calculated this way is less meaningful for children or the very elderly.
Is ideal weight the same as a healthy BMI weight?
They’re related but not identical. BMI-based ranges depend only on height, while formulas like Devine and Robinson were derived from different reference populations, so the two can give slightly different “healthy” numbers.
Should athletes use this calculator?
Treat the result loosely. Athletes with a lot of muscle often weigh more than their calculated ideal weight while still being lean and healthy, since none of these formulas account for muscle mass.
Does switching between metric and imperial change the result?
No — the calculator converts your height to inches internally before applying the formulas, so metric and imperial inputs for the same height give the same ideal weight.
About the ideal weight calculator
This calculator estimates your ideal body weight from your height and sex, using several well-known formulas at once. Ideal body weight is a number doctors and dietitians use as a reference point — for setting health goals, and in medicine for working out drug doses. Because it depends only on height and sex, it is a starting point rather than a precise target, and it is best read alongside measures like BMI and body fat.
How to use it
Choose your sex, pick metric or imperial units, and enter your height. The calculator returns the Devine estimate as the headline figure, plus the Robinson, Miller and Hamwi results and a healthy weight range from BMI. For example, a man of 178 cm has a Devine ideal weight of about 73 kg, with the other formulas landing within a few kilograms. The spread between them shows why ideal weight is a range, not a single magic number.
The formula
The Devine formula is , where is the weight in kilograms, is a base of 50 kg for men or 45.5 kg for women, and is height in inches. In words, it starts from a base weight for a 5-foot person and adds 2.3 kg for every inch above that. The Robinson, Miller and Hamwi formulas follow the same shape with slightly different constants, which is why their answers differ a little.
Where it is used
Doctors use ideal body weight to calculate doses for certain medicines and to set ventilator settings, where the right amount depends on lean size rather than actual weight. Dietitians use it as a reference when discussing weight goals, and it appears in fitness and nutrition apps. Athletes and coaches treat it cautiously, since a lot of muscle pushes real weight above the “ideal” without any health concern.