CalcVitalsIdeal Weight Calculator
The Devine formula gives an ideal weight of 50 kg plus 2.3 kg for every inch over 5 feet for a man. For example, a man of 175 cm gets an ideal weight of 70.5 kg — comfortably inside his healthy BMI range of 56.7–76.3 kg.
How it works
The 'ideal weight' formulas all start from the same simple idea: take a base weight at 5 feet tall, then add a fixed amount for every inch above it. Devine's 1974 version — 50 kg for a man, 45.5 kg for a woman, plus 2.3 kg per inch — became the most used because pharmacists adopted it for drug dosing, not because it was ever a description of a perfect body.
Robinson, Miller and Hamwi each refitted the same shape of formula to different data, which is why this page shows all four together. When independent formulas land near each other, the zone they form is a reasonable orientation point. When someone quotes you a single ideal weight to the nearest kilogram, they are claiming a precision the underlying science never had.
The healthiest way to use these numbers is as the centre of the healthy BMI range for your height, not as a target to chase at any cost. Frame size, muscle mass and where you carry weight all move what 'ideal' means for one particular body — the formulas know none of that.
The method
Devine (1974): men 50 kg + 2.3 kg per inch over 5 ft; women 45.5 kg + 2.3 kg per inch. Robinson (1983): 52/49 kg + 1.9/1.7 kg per inch. Miller (1983): 56.2/53.1 kg + 1.41/1.36 kg per inch. Hamwi (1964): 48/45.5 kg + 2.7/2.2 kg per inch. Healthy range shown from BMI 18.5–24.9.
Frequently asked questions
Which formula should I believe?
None of them individually — believe the cluster. They were built for dosing and insurance tables, and they bracket a sensible zone. The Devine figure is shown largest only because it is the most widely used reference.
My ideal weight is below the healthy BMI range — what gives?
That can happen at shorter heights, where the per-inch additions shrink faster than the BMI band. Where the formula and the BMI range disagree, the BMI range is the better guide, and a clinician who knows you beats both.
Does frame size matter?
The original Hamwi method adjusted ±10% for frame size, which is an admission that one line cannot fit every build. Broad frames and muscular builds sit sensibly at the top of the zone or above it.