Ideal Weight Calculator
The four standard ideal-body-weight formulas, side by side, plus the healthy BMI range — because a single “ideal” number was never the honest answer.
Devine (1974)
156 lb (70.7 kg)
Robinson (1983)
152 lb (69.1 kg)
Miller (1983)
152 lb (68.9 kg)
Hamwi (1964)
159 lb (72.3 kg)
Healthy BMI range (18.5–24.9)
125–169 lb (57–76 kg)
These formulas were built for drug dosing, not aesthetics — they ignore body composition entirely, so a muscular person can be perfectly healthy well above every number here. Treat the spread across formulas as the honest range. Educational use only.
Where These Formulas Come From
None of them were designed as health targets. Hamwi (1964) was a quick rule of thumb for diabetic diet planning; Devine (1974) was built to dose medications like gentamicin, and it remains the standard in pharmacy today; Robinson and Miller (both 1983) are refinements fitted to actuarial height-weight data. They agree within a few pounds at average heights and drift apart at the extremes — which is the real reason to look at all four plus the BMI band rather than any single number.
Formulas (kg; h = inches over 5 ft)
Devine: M: 50.0 + 2.3h F: 45.5 + 2.3h Robinson: M: 52.0 + 1.9h F: 49.0 + 1.7h Miller: M: 56.2 + 1.41h F: 53.1 + 1.36h Hamwi: M: 48.0 + 2.7h F: 45.5 + 2.2h Healthy BMI band: 18.5–24.9 × height(m)²
Frequently Asked Questions
Why do the four ideal-weight formulas give different answers?
They were fitted decades apart for different purposes — Hamwi for diabetic diet planning (1964), Devine for drug dosing (1974), Robinson and Miller as actuarial refinements (1983). At average heights they cluster within a few pounds; at very tall or short heights they spread. The honest reading is the range, not one line.
Is 'ideal weight' the same as a healthy weight?
No. The formulas ignore body composition completely — a muscular athlete can exceed every formula and be healthier than someone who matches them exactly. The BMI band (18.5–24.9) defines the statistically healthy range; body fat percentage says far more about an individual than scale weight.
Why do pharmacists still use the Devine formula?
Some drugs distribute mainly in lean tissue rather than fat, so dosing by total body weight would overdose larger patients. Devine's ideal body weight (or an adjusted version of it) approximates lean mass well enough for those calculations — it's the formula's original and still most legitimate job.
How much should a 5'9" person weigh?
The four formulas put a 5'9" man at roughly 152–159 lb and a woman at 142–146 lb, while the healthy-BMI band spans about 125–169 lb for either. That 40-pound spread is the real answer: frame size, muscle, and body fat determine where in the band a healthy weight sits.