Your result
What your result means
For a height of 5 ft 9 in, the four formulas give between 151.9 lb – 159.4 lb; the Devine formula, the one most often used in clinical settings, gives 155.9 lb. A broader way to think about it is the healthy-BMI range of 125 lb – 169 lb.
The math
Formula and sources
IBW = base + increment × (height in inches − 60) Devine men 50 + 2.3 women 45.5 + 2.3 Robinson men 52 + 1.9 women 49 + 1.7 Miller men 56.2 + 1.41 women 53.1 + 1.36 Hamwi men 48 + 2.7 women 45.5 + 2.2 (kg)
- IBW
- ideal body weight in kg
- 60
- five feet, the base height of every formula
These formulas were designed for drug dosing, not as personal weight goals. They ignore frame size, muscle and age.
Sources we checked this against
- 1Pai MP, Paloucek FP. The origin of the “ideal” body weight equations (Ann Pharmacother, 2000)PubMed / NIH National Library of Medicine · pubmed.ncbi.nlm.nih.gov
- 2Fundamentals of Pharmacy Calculations – Ideal body weight (Devine)OER Commons · oercommons.org
- 3Adult BMI Categories / BMI Frequently Asked QuestionsCenters for Disease Control and Prevention · cdc.gov
Formula last checked 2026-11-04. Found an error? Tell us and we will fix it.
Step by step
Two worked examples
Textbook example: woman, 5 ft 5 in
Devine (1974)
125.7 lb
- Sex
- Female
- Units
- US (ft, in, lb)
- Height (feet)
- 5 ft
- Height (inches)
- 5 in
45.5 + 2.3 × 5 = 57 kg, the answer in the pharmacy-calculations textbook. In pounds that is 125.7 lb; the healthy BMI range is 111 lb – 150 lb.
Textbook example: man, 5 ft 11 in
Devine (1974)
166 lb
- Sex
- Male
- Units
- US (ft, in, lb)
- Height (feet)
- 5 ft
- Height (inches)
- 11 in
50 + 2.3 × 11 = 75.3 kg (166 lb). Robinson gives 160.7 lb and Hamwi 171.3 lb.
| Result | Example 1 | Example 2 |
|---|---|---|
| Devine (1974) | 125.7 lb | 166 lb |
| Robinson (1983) | 126.8 lb | 160.7 lb |
| Hamwi (1964) | 124.6 lb | 171.3 lb |
| Healthy BMI range (18.5–24.9) | 111 lb – 150 lb | 133 lb – 179 lb |
Questions
Frequently asked questions
Which formula is best?
None is clearly best; they were fitted to different data decades ago. Devine is the most widely used in hospitals. The healthy BMI range is a better guide for personal goals.
Why does ideal weight not depend on age?
The formulas were built for dosing calculations in adults and only use height and sex. Health risk at a given weight does change with age, which is another reason to treat IBW as a reference only.
What if I am under 5 feet?
The formulas subtract the increment for each inch below 60, but they were not designed for that range, so treat results as rough.