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A reference weight for a given height: 50 kg for a man or 45.5 kg for a woman at 60 inches, plus 2.3 kg for every inch above. Devised for drug dosing, not as a target.
In Swedish: Idealvikt (Devine)
IBW
A reference weight for a given height: 50 kg for a man or 45.5 kg for a woman at 60 inches (152.4 cm), plus 2.3 kg for every inch above. It was devised for drug dosing, not as a target (McCarron and Devine, 1974).
IBW=73
IBW equals 50 plus (2.3 times ((177.8 divided by 2.54) minus 60)), equals 50 plus (2.3 times (70 minus 60)), equals 50 plus (2.3 times 10), equals 50 plus 23, equals 73
You are given
Round to 1 decimal.
Source: McCarron MM, Devine BJ (1974). Clinical pharmacy: case studies, case number 25, gentamicin therapy. Drug Intelligence & Clinical Pharmacy 8(11), 650–655. (coefficients read in Briguglio M, Wainwright TW, Lombardi G (2023). Definition of malnutrition from routinely-collected data for orthopedic surgery research. Frontiers in Nutrition 10, 1200049.) — checked October 19, 2026
h is the height in centimetres, h / 2.54 the same height in inches, and s the base weight: 50 kg for a man, 45.5 kg for a woman. Every inch above 60 inches (152.4 cm) adds 2.3 kg.
Holds when the height is above 60 inches. Below that the bracket is negative and the formula gives less than its base weight, which Devine never intended; the equation was written for adults in the range of the height–weight tables it came from.
A man of 177.8 cm, which is 70 inches: IBW = 50 + 2.3 · 10 = 73.0 kg. A woman of 165.1 cm, 65 inches: 45.5 + 2.3 · 5 = 57.0 kg.
Devine published the equation in 1974 to dose gentamicin, an antibiotic whose dose should follow lean weight rather than total weight. It has stayed in use for that purpose, and for setting ventilator volumes, because it is simple and in inches. Pai and Paloucek (2000) traced the history: the several ideal-weight equations agree with each other because they were all read off the same insurance height–weight tables.
The formula ignores build, age, muscle and where fat sits, and a healthy weight for a given height is a range, not a point. A fit person of 177.8 cm can weigh 85 kg and be in better health than one who weighs 73. For a judgment about weight, the BMI with its range and the waist-to-height ratio are the measures made for it.
Why inches?
Because it was written in the United States in 1974 for American clinicians. The card above converts
from centimetres.
Are there other ideal-weight formulas?
Robinson (1983) and Miller (1983) are two; they differ from Devine by a kilogram or two over the usual
range and have the same origin.
What about the Lorentz formula?
A European rule of thumb from the 1920s with no primary source in the collection, so it is not here.
| Solve for | Rearranged | With the numbers | Comes to |
|---|---|---|---|
| h | 2.54(60 | 2.54(60 | 177.8 |
| s | IBW | 73 | 50 |
| IBW | s | 50 | 73 |
Last reviewed October 20, 2026 ·How pages are reviewed
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