Breakdown
How it works
The healthy BMI range (18.5–24.9) gives a weight band for your height. The named formulas date from drug-dosing research and give a single number that ignores frame size and muscle; they typically sit in the lower half of the healthy range.
Formula
Healthy range = 18.5 × h² to 24.9 × h² (h in metres)
Devine (men) = 50 + 2.3 × inches over 5 ft; (women) 45.5 + 2.3 × inches
Worked example
175 cm male: healthy 56.7–76.3 kg; Devine 70.5, Robinson 68.9, Miller 68.8, Hamwi 72.1 kg.
Frequently asked questions
Which formula is best?
None is clinically superior. Robinson and Miller are the most moderate; use the BMI range plus waist measurement.
Does age change ideal weight?
Slightly — some evidence supports a BMI up to 27 over 65. Muscle preservation matters more than the scale number.
What about athletes?
BMI and these formulas over-estimate fatness in muscular people; use body fat percentage instead.