Ideal Weight Formulas 2025: Devine vs Robinson vs Miller vs Hamwi Compared
Core Conclusion
All four ideal body weight formulas share the linear structure: baseline weight at 5 feet plus a per-inch coefficient. G.J. Hamwi (1964) male = 48 kg + 2.7 kg/in over 5ft, female = 45.5 kg + 2.2 kg/in. B.J. Devine (1974) male = 50 kg + 2.3 kg/in, female = 45.5 kg + 2.3 kg/in. Robinson (1983) male = 52 kg + 1.9 kg/in, female = 49 kg + 1.7 kg/in. Miller et al. (1983) male = 56.2 kg + 1.41 kg/in, female = 53.1 kg + 1.36 kg/in. These formulas were developed for pharmaceutical dosing reference, not as individual clinical diagnostic metrics.
Ideal body weight formulas occupy a curious position in the clinical and statistical literature. Four formulations — Hamwi (1964), Devine (1974), Robinson (1983), and Miller et al. (1983) — continue to appear in pharmacy references, clinical calculators, and textbook appendices decades after their initial publication. Each uses the same underlying linear mathematical structure, yet specifies different baseline weight values and different per-inch height coefficients. This page documents each formula from its original published source, lists the exact coefficients as printed, compares all four outputs side by side across the adult height range from 5 feet 0 inches through 6 feet 4 inches, and explains the historical context in which these equations were developed and deployed.
Readers seeking a lookup table for published height-to-weight reference ranges can consult the [Standard Weight Chart + ../tools/standard-weight-chart.html] which presents BMI-derived population weight bands for each height centimeter. The [Height-Weight Ratio Tool + ../tools/height-weight-ratio.html] implements visual grid positioning, and the [BMI Calculator + ../tools/bmi-calculator.html] computes the weight-height ratio used in WHO classification systems.
Why "Ideal Weight" Is a Statistical Reference Not a Prescription
The term "ideal body weight" (abbreviated IBW in the clinical literature) is potentially misleading to readers encountering it for the first time. The word "ideal" in this context is a term of art drawn from mid-twentieth-century pharmaceutical practice, not a value judgment about what any individual person "should" weigh. In the papers that introduced these formulas, "ideal" referred to a weight value selected as a convenient computational reference point for a specific narrow technical purpose: estimating weight-based drug dosages when direct weight measurement was unavailable or when dosing guidance called for a body-size adjustment term.
None of the four original papers (Hamwi, Devine, Robinson, Miller) proposed that their formula output represented a clinically optimal weight for any specific individual, nor did they suggest using these formulas as screening or diagnostic instruments. The formulas were derived as statistical population summaries and recommended for use only within the narrow dosing contexts for which they were originally validated. Readers encountering IBW values in modern references should interpret them as historical reference numbers drawn from 1960s through 1980s pharmaceutical literature, not as contemporary individual health targets.
The standard pattern across all four formulas is a linear function of height above a 5-foot (60-inch, 152.4 cm) baseline. The general form, common to Hamwi, Devine, Robinson, and Miller alike, is: IBW = baseline_kg + coefficient_kg_per_inch × (height_inches − 60). The 60-inch subtraction means that a person whose height is exactly 5 feet receives a computed IBW equal to the baseline value. Each additional inch of height above 5 feet adds the per-inch coefficient to the total. The formulas diverge from one another in two parameters only: the baseline weight assigned at exactly 5 feet, and the coefficient assigned per additional inch above 5 feet. Some formulas also assign sex-specific values to both parameters, while others assign identical coefficients to both sexes.
G.J. Hamwi 1964 Formula
The earliest of the four formulations under comparison was published by G.J. Hamwi in 1964. Hamwi's work appeared in clinical nutrition and pharmacy literature of the period and was subsequently propagated widely in pharmacy and medical textbooks. Hamwi proposed sex-specific baselines and sex-specific per-inch coefficients, making his formula the only one of the four with both distinct baselines and distinct per-inch increments across sexes.
Hamwi 1964 Male Formula
IBWmale (Hamwi) = 48 kg + 2.7 kg × (height_inches − 60)
Where height_inches is total stature measured in inches, and 60 corresponds exactly to 5 feet (152.4 cm). A male who is exactly 5 feet tall receives a computed Hamwi IBW of 48.0 kg. Each additional inch adds 2.7 kg.
Hamwi 1964 Female Formula
IBWfemale (Hamwi) = 45.5 kg + 2.2 kg × (height_inches − 60)
A female who is exactly 5 feet tall receives a computed Hamwi IBW of 45.5 kg. Each additional inch adds 2.2 kg. The female Hamwi baseline is 2.5 kg below the male baseline, and the female per-inch increment is 0.5 kg below the male per-inch increment, reflecting the two-sex model Hamwi adopted from the mid-century clinical nutrition references available to him at time of publication.
B.J. Devine 1974 Formula
B.J. Devine published the second major IBW formulation in 1974 in the journal Drug Intelligence and Clinical Pharmacy. Devine's paper addressed the same narrow pharmaceutical use case — estimating appropriate dosages for medications whose dosing schedules called for weight adjustment — and proposed updated coefficients relative to Hamwi's 1964 work. Devine's formula has become the most widely cited IBW equation in subsequent literature and the one most commonly implemented in clinical dosing calculators through the 1990s and 2000s.
Devine 1974 Male Formula
IBWmale (Devine) = 50 kg + 2.3 kg × (height_inches − 60)
A male exactly 5 feet tall receives a Devine IBW of 50.0 kg, which is 2.0 kg above the corresponding Hamwi male baseline. Each additional inch of height adds 2.3 kg under the Devine male specification, which is 0.4 kg per inch less than the corresponding Hamwi male coefficient of 2.7 kg per inch.
Devine 1974 Female Formula
IBWfemale (Devine) = 45.5 kg + 2.3 kg × (height_inches − 60)
The Devine female baseline at exactly 5 feet is 45.5 kg, identical to the Hamwi female baseline. However, Devine adopted a single unified per-inch coefficient of 2.3 kg for both sexes, whereas Hamwi had used a female-specific 2.2 kg per inch. Devine's female formula therefore adds 0.1 kg more per inch above 5 feet than the corresponding Hamwi female formula. For a 5-foot-8-inch female, Devine's IBW is approximately 0.8 kg above Hamwi's; for a 6-foot female, the gap widens to approximately 1.2 kg.
Robinson 1983 Revised Formulas
Robinson and colleagues published the third major IBW formulation in 1983 in the Annals of Internal Medicine. The Robinson paper drew on data from the NHANES (National Health and Nutrition Examination Survey) population datasets, which had become available by the early 1980s and provided substantially larger and more nationally representative anthropometric samples than were accessible to Hamwi in 1964 or Devine in 1974. Robinson proposed both revised baseline weights and revised per-inch coefficients for both sexes.
Robinson 1983 Male Formula
IBWmale (Robinson) = 52 kg + 1.9 kg × (height_inches − 60)
At 5 feet exactly, the Robinson male baseline of 52 kg sits 2 kg above Devine's 50 kg baseline and 4 kg above Hamwi's 48 kg baseline. But Robinson's per-inch coefficient of 1.9 kg per inch is substantially lower than Devine's 2.3 kg and Hamwi's 2.7 kg. This means that Robinson's male curve crosses below both Devine and Hamwi at taller heights. For example, at 5 feet 5 inches, Robinson male = 61.5 kg, Devine = 61.5 kg (they are equal); above 5 feet 5 inches, Robinson falls progressively below Devine and Hamwi as height increases.
Robinson 1983 Female Formula
IBWfemale (Robinson) = 49 kg + 1.7 kg × (height_inches − 60)
The Robinson female baseline at exactly 5 feet is 49 kg, which is 3.5 kg above the Devine and Hamwi female baseline of 45.5 kg. Robinson's female per-inch coefficient of 1.7 kg is lower than Devine's 2.3 kg and Hamwi's 2.2 kg. The Robinson female curve crosses below the Devine female curve at approximately 5 feet 6 inches, and below the Hamwi female curve at approximately 5 feet 8 inches, reflecting the same "higher baseline, lower slope" pattern seen in the male comparison.
Miller et al. 1983 Update
Miller and his co-authors published the fourth of the major IBW formulations in 1983 in the American Journal of Medicine. Miller's work appeared in the same year as Robinson's paper and drew on similar population-level datasets. The Miller formula adopts the most extreme parameter values of the four formulas under comparison: it has the highest baseline weight at exactly 5 feet for both sexes and the lowest per-inch coefficient for both sexes. This combination produces the flattest IBW-to-height relationship across the adult stature range.
Miller 1983 Male Formula
IBWmale (Miller) = 56.2 kg + 1.41 kg × (height_inches − 60)
At exactly 5 feet, Miller's male baseline of 56.2 kg sits 4.2 kg above Robinson's 52 kg, 6.2 kg above Devine's 50 kg, and 8.2 kg above Hamwi's 48 kg. The Miller male per-inch coefficient of 1.41 kg is the lowest of the four formulas — 0.49 kg per inch below Robinson, 0.89 kg below Devine, and 1.29 kg below Hamwi. Due to the very high baseline combined with the very low slope, Miller male IBW values are the highest of the four formulas at heights below approximately 6 feet 1 inch and fall below the Devine and Hamwi curves only at the tallest end of the adult male stature range (6 feet 2 inches and above).
Miller 1983 Female Formula
IBWfemale (Miller) = 53.1 kg + 1.36 kg × (height_inches − 60)
At exactly 5 feet, Miller's female baseline of 53.1 kg is 4.1 kg above Robinson's 49 kg baseline and 7.6 kg above the Devine/Hamwi shared baseline of 45.5 kg. The Miller female per-inch coefficient of 1.36 kg is the lowest among the four female formulas — 0.34 kg below Robinson, 0.94 kg below Devine, and 0.84 kg below Hamwi. The Miller female curve produces the highest IBW of the four formulas across the entire practical adult female height range from 5 feet through approximately 6 feet 4 inches, crossing below the other curves only at extreme heights well beyond the 99th population percentile.
Detailed Comparison Table (Height 5'0" through 6'4" — All Four Formulas in kg)
The table below presents computed ideal body weight in kilograms for male and female statures from 5 feet 0 inches through 6 feet 4 inches in one-inch increments. All four formulas (Hamwi, Devine, Robinson, Miller) are shown side by side for direct visual comparison. Computed values are rounded to one decimal place.
| Height (ft/in) | Height (cm) | Hamwi Male (kg) | Devine Male (kg) | Robinson Male (kg) | Miller Male (kg) |
|---|---|---|---|---|---|
| 5'0" | 152.4 | 48.0 | 50.0 | 52.0 | 56.2 |
| 5'2" | 157.5 | 53.4 | 54.6 | 55.8 | 59.0 |
| 5'4" | 162.6 | 58.8 | 59.2 | 59.6 | 61.8 |
| 5'6" | 167.6 | 64.2 | 63.8 | 63.4 | 64.7 |
| 5'8" | 172.7 | 69.6 | 68.4 | 67.2 | 67.5 |
| 5'10" | 177.8 | 75.0 | 73.0 | 71.0 | 70.3 |
| 6'0" | 182.9 | 80.4 | 77.6 | 74.8 | 73.2 |
| 6'2" | 188.0 | 85.8 | 82.2 | 78.6 | 76.0 |
| 6'4" | 193.0 | 91.2 | 86.8 | 82.4 | 78.8 |
Worked Calculation Example: 5'8" (172.7 cm) Male Across All Four Formulas
A stature of 5 feet 8 inches corresponds to 68 total inches, which is 8 inches above the 5-foot (60-inch) baseline. The reference computations for all four formulas for a 5-foot-8-inch male proceed as follows.
Hamwi 1964 — 5'8" Male
IBW = 48.0 kg + 2.7 kg/in × 8 in = 48.0 + 21.6 = 69.6 kg
Devine 1974 — 5'8" Male
IBW = 50.0 kg + 2.3 kg/in × 8 in = 50.0 + 18.4 = 68.4 kg
Robinson 1983 — 5'8" Male
IBW = 52.0 kg + 1.9 kg/in × 8 in = 52.0 + 15.2 = 67.2 kg
Miller 1983 — 5'8" Male
IBW = 56.2 kg + 1.41 kg/in × 8 in = 56.2 + 11.28 = 67.5 kg (rounded to 67.5 kg)
For this 5-foot-8-inch example, the four formula outputs span a 2.4 kg range: from 67.2 kg (Robinson) at the low end to 69.6 kg (Hamwi) at the high end, with Devine at 68.4 kg and Miller at 67.5 kg falling near the middle of the distribution. This range across formulas for the same height is typical and underscores the observation that IBW is a family of related but distinct statistical reference values, not a single unique number.
How IBW Was Historically Used for Pharmaceutical Drug Dosing
The primary historical application of ideal body weight formulas in clinical pharmacy practice was the estimation of dosing for weight-based medications in situations where actual measured body weight was either not available or where clinical dosing guidelines called explicitly for an "ideal" or "adjusted" body weight term rather than actual total body weight. Medications historically dosed using IBW calculations include certain classes of antibiotics (notably aminoglycosides such as gentamicin and tobramycin), anticoagulant compounds (notably unfractionated heparin), and a subset of oncology chemotherapeutic agents whose published dosing nomograms referenced IBW or adjusted body weight rather than actual weight.
A common pattern in dosing guidelines of the 1980s and 1990s was the use of IBW for individuals whose actual weight significantly exceeded population reference values, combined in some protocols with an adjusted body weight formula that interpolated between IBW and actual body weight using a correction factor (commonly 0.4 or 0.25 depending on the specific medication and guideline). These dosing practices varied across institutions and across specific drug classes, and contemporary pharmaceutical guidance has in many cases moved toward actual-weight-based dosing protocols or toward alternate body size estimators such as lean body weight or adjusted ideal body weight formulas specific to each medication class.