There is no single perfect weight, but doctors have used several formulas for decades to define a reasonable range. This calculator runs the classics side by side. The Devine formula, originally created for drug dosing, gives 50 kilograms plus 2.3 kilos for every inch over 5 feet for men, and 45.5 plus 2.3 per inch for women. The Miller formula uses a gentler slope — 56.2 plus 1.41 per inch for men, 53.1 plus 1.32 for women. Robinson and Hamwi variants exist too, and seeing them together shows how much expert estimates can differ.

Take a 5-foot-9 man in Seattle. Devine puts his ideal near 156 pounds; Miller suggests about 165. That nine-pound spread is the point: these are reference ranges, not verdicts. Body frame, muscle mass, and age all shift where any individual feels and performs best. The formulas were built from population data and insurance tables, not from measuring what makes a particular person healthy.

Use the results as a conversation starter with your doctor or as a sanity check on a fitness goal — not as a target to chase at any cost. Anyone with a history of disordered eating should skip ideal-weight numbers entirely and work directly with a professional.

With the pre-filled defaults — Height (cm) 170 — the Ideal Weight Calculator returns Height above 5ft (inches) 6.9, Devine (male) kg 65.9, Devine (female) kg 61.4, Miller (male) kg 66.0, Miller (female) kg 62.5. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.