Ideal Body Weight Calculator (US lb/in)
This calculator estimates ideal body weight using four classic height-based formulas: Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). All results are displayed in US pounds for height in inches. Results update in real time as you type.
Height & Gender Input (US Units)
Results update in real time as you type — no Calculate button needed.
Ideal Weight Formulas (US lb/in)
All four formulas are two-part linear models: a baseline weight at 5 feet of height plus a fixed increment per additional inch. Below are the formulas converted to US imperial units (lb and in). The height-over-5-ft term uses max(0, height_in − 60).
| Formula | Male (lb) | Female (lb) | Year |
|---|---|---|---|
| Hamwi | 106 + 6 × (in over 5 ft) | 100 + 5 × (in over 5 ft) | 1964 |
| Devine | 110.2 + 5.07 × (in over 5 ft) | 100.3 + 5.07 × (in over 5 ft) | 1974 |
| Robinson | 114.6 + 4.14 × (in over 5 ft) | 108.0 + 3.74 × (in over 5 ft) | 1983 |
| Miller | 123.9 + 3.12 × (in over 5 ft) | 117.0 + 3.02 × (in over 5 ft) | 1983 |
Origins of the Four Formulas
The Hamwi formula was published in 1964 by G.J. Hamwi and was based on data from life insurance studies. It is one of the oldest and most widely cited height-weight relationships. The Devine formula was developed in 1974 for the purpose of estimating ideal body weight for drug dosing and ventilator settings in critical care. It uses the 50 kg (110.2 lb) and 45.5 kg (100.3 lb) baselines with a 2.3 kg (5.07 lb) per-inch increment.
The Robinson and Miller formulas were both published in 1983 using data from the US National Health and Nutrition Examination Survey (NHANES). Robinson uses a higher baseline (52 kg male / 49 kg female) with a moderate per-inch increment, while Miller uses an even higher baseline (56.2 kg male / 53.1 kg female) with a smaller increment, reflecting a different regression fit to the same NHANES population.
Critical Caveats
Ideal body weight formulas were developed for clinical dosing reference, not for health or weight management targets. They do not account for lean mass, body fat distribution, age-related changes in body composition, bone density, or ethnicity. For a more meaningful assessment, use BMI ranges, body fat percentage, waist circumference, and other validated health metrics. The calculator is provided for educational reference only.
Frequently Asked Questions
- All four formulas use a two-part linear model: a baseline weight at 5 feet of height, plus a constant increment per additional inch. They differ in both the baseline and the per-inch increment.
- None is definitively most accurate. Each was derived from a specific population. Hamwi used insurance data, Devine was developed for drug dosing, Robinson and Miller used NHANES data. All should be treated as historical references.
- Differences arise from the study populations (age, gender, ethnicity), the outcome variable used, and the regression method. Baseline weights and per-inch increments vary, producing diverging estimates especially at extreme heights.
- No. Ideal body weight formulas were developed for drug dosing and ventilation in clinical settings, not as health targets. Healthy weight is better characterized by BMI ranges and body composition.