Four formulas have been used since the 1960s to put a single number on 'ideal' body weight. They disagree with each other by several kilograms, and none was actually derived to define health — which is the most useful thing to know about them.
- Formulas shown
- Devine, Robinson, Miller, Hamwi
- Structure
- Base weight at 5 ft plus a per-inch increment
- Devine's original purpose
- Calculating drug doses
- Clinically preferred
- The healthy BMI range, 18.5–24.9
- Not valid for
- Children, pregnancy, very muscular builds
Formula
Devine (1974), shown alongside Robinson (1983), Miller (1983) and Hamwi (1964)Devine (men): 50 kg + 2.3 kg per inch over 5 ft Devine (women): 45.5 kg + 2.3 kg per inch over 5 ft
- inches over 5 ft
- — Height in inches minus 60
All four share this base-plus-increment structure and differ only in the constants. Below 5 feet they extrapolate downward — a region none of the original papers validated, so results for shorter heights should be treated with caution.
Ideal Weight Calculator examples
| Input | Result | Category |
|---|---|---|
| Man, 5'8" | 150.3 lb | Average of four formulas |
| Man, 5'10" | 159.4 lb | Average of four formulas |
| Man, 6'0" | 168.6 lb | Average of four formulas |
| Woman, 5'2" | 114.8 lb | Average of four formulas |
| Woman, 5'5" | 127.3 lb | Average of four formulas |
| Woman, 5'8" | 139.8 lb | Average of four formulas |
Where these formulas came from
Understanding their origins explains why they should not be read as health targets.
- Hamwi (1964) — devised as a quick bedside method for estimating calorie needs in diabetic patients.
- Devine (1974) — created to standardise drug dosing, particularly for medicines distributed in lean tissue. It remains in clinical use for exactly that, and is still how gentamicin and similar drugs are dosed.
- Robinson (1983) and Miller (1983) — both revisions fitted to updated population data from insurance tables.
None was derived from mortality or morbidity outcomes. They describe averages from mid-century insurance data, which is a different thing from describing the weight at which a person is healthiest.
Why a range beats a single number
Two people of the same height and sex can be healthy at weights 15 kg apart, depending on frame size, muscle mass, and fat distribution. A single 'ideal' figure cannot express that.
The healthy BMI range shown alongside the formulas — 18.5 to 24.9 — is what clinicians actually use, and it is deliberately wide. Within it, mortality and cardiometabolic risk are broadly flat, so there is no advantage in aiming for a particular point inside it.
Frame size and muscle
None of the formulas accounts for skeletal frame or body composition, and both move the answer meaningfully.
Older clinical practice adjusted by roughly 10% downward for a small frame and 10% upward for a large one, judged by wrist circumference or elbow breadth. Muscle matters more: a trained athlete can sit well above every formula's output while carrying low body fat, exactly as they can register as overweight by BMI.
If your weight sits above these figures, body fat percentage and waist circumference will tell you far more than any further precision on the ideal-weight number.
Where ideal body weight is still genuinely used
Devine's formula remains standard in two clinical settings, neither of which is telling patients what to weigh.
- Drug dosing — medicines that distribute into lean tissue rather than fat are dosed on ideal or adjusted body weight, so an obese patient is not overdosed.
- Mechanical ventilation — tidal volumes are set per kilogram of predicted body weight, calculated from height and sex, because lung size tracks height rather than weight.
Frequently asked questions
What is my ideal weight for my height?
The four classic formulas typically land within a few kilograms of each other near BMI 21–23. A more useful answer is the healthy BMI range for your height, 18.5 to 24.9, since any weight within that band is considered healthy.
Which ideal weight formula is most accurate?
None is more accurate than the others, because they were not measuring the same thing. Devine is the most widely used clinically, but for drug dosing rather than health. For assessing your own weight, the BMI range is the better reference.
Is ideal body weight different for men and women?
Yes. Every formula uses a lower base weight for women at the same height, reflecting differences in average lean mass and frame size. The gap is roughly 4 to 5 kilograms at 5 feet, widening slightly with height.
Should I aim for my ideal body weight?
Not necessarily. These formulas describe mid-century population averages, not personal health targets. If you are within the healthy BMI range with a reasonable waist measurement, there is no evidence that moving toward a specific formula's number improves anything.
Do these formulas work if I am under 5 feet tall?
They extrapolate below 5 feet but were never validated there, and can produce implausibly low figures. For shorter heights, use the healthy BMI weight range instead, which scales correctly across the whole range.
What if I am very muscular?
These formulas will underestimate a healthy weight for you, as BMI does, because neither can distinguish muscle from fat. Body fat percentage and waist circumference give a far more meaningful assessment for muscular builds.
Sources
- Gentamicin therapy (the paper introducing the Devine formula) — Devine, Drug Intelligence and Clinical Pharmacy, 1974
- Determination of ideal body weight for drug dosage calculations — Robinson et al., American Journal of Hospital Pharmacy, 1983
- About Adult BMI — Centers for Disease Control and Prevention, 2024
- Ventilation with lower tidal volumes for acute lung injury and ARDS (predicted body weight in practice) — ARDS Network, New England Journal of Medicine, 2000