Ideal Weight Calculator
Enter your height and sex to see the weight range that falls in the World Health Organization’s normal BMI range, next to the results of the Hamwi, Devine, Robinson and Miller “ideal body weight” formulas.
- Hamwi (1964)56.6 kg
- Devine (1974)56.9 kg
- Robinson (1983)56.9 kg
- Miller (1983)59.8 kg
How it is calculated
“Ideal body weight” formulas are conventions used in drug dosing and clinical calculations, not health targets. Hamwi’s 1964 rule appeared in the dietary-therapy chapter of an American Diabetes Association book on diabetes; Devine’s 1974 formula was published in a case report on gentamicin (an antibiotic) dosing. As Pai and Paloucek (2000) review, Devine’s formula spread because the pharmacokinetics of certain drugs were found to correlate with this weight, and it agrees with an older rule derived from height-weight tables; in 1983 Robinson and colleagues derived formulas by regression on the Metropolitan Life insurance height-weight tables, and Miller and colleagues published similar ones the same year. The same review explains that height-weight tables were made to compare populations by relative weight and that these weights were called “desirable” or “ideal” once they were found to correlate with mortality; the formulas look alike because the tables behind them agree. All four are written for a base height of 5 ft (152.4 cm) and are not defined for shorter people. For judging an adult’s weight for health, the international measure is the World Health Organization’s BMI classification: 18.5 to 24.99 kg/m² is the normal range.
Formula weight = base + coefficient × (height − 152.4 cm) ÷ 2.54 · Normal range = BMI limit × height² (m²)Base and coefficient (kg; male / female): Hamwi 106 lb + 6 lb / 100 lb + 5 lb (1 lb = 0.45359237 kg); Devine 50 + 2.3 / 45.5 + 2.3; Robinson 51.65 + 1.85 / 48.67 + 1.65; Miller 56.2 + 1.41 / 53.1 + 1.36. (height − 152.4) ÷ 2.54 is the number of inches over 5 ft.- Subtract 152.4 cm (5 ft) from the height and divide by 2.54 to get the inches over 5 ft.
- For each formula multiply that by the coefficient and add the base; convert Hamwi’s pounds to kilograms.
- Below 152.4 cm the formulas are not defined, so they are not calculated.
- For the normal range multiply the height in metres squared by WHO’s normal BMI limits; the tool gives the lightest and heaviest weight, in 0.1 kg steps, whose BMI to two decimals is in that range.
Example
For a 165 cm woman the height over 5 ft is (165 − 152.4) ÷ 2.54 = 4.96 in. Hamwi 45.36 + 2.27 × 4.96 = 56.6 kg; Devine 45.5 + 2.3 × 4.96 = 56.9 kg; Robinson 48.67 + 1.65 × 4.96 = 56.9 kg; Miller 53.1 + 1.36 × 4.96 = 59.8 kg. With 1.65² = 2.7225 the normal BMI range is 50.4–68.0 kg.
Frequently asked questions
Which ideal weight formula is right?
None has been validated as a personal target. The formulas are conventions used in drug dosing and give results a few kilograms apart for the same height. For a healthy weight the reference is WHO’s BMI range (18.5–24.99 kg/m²); ask your doctor or a dietitian about your own case.
What if I am shorter than 152 cm?
The formulas add weight for each inch over 5 ft (152.4 cm); their authors gave no rule below that height. In that case the tool does not calculate them and shows only the WHO normal-BMI weight range for your height.
Why does the Robinson result differ from other sites?
This tool uses the coefficients published in Robinson and colleagues’ 1983 paper (male 51.65 + 1.85 kg, female 48.67 + 1.65 kg per inch). Many sources quote a rounded form (52 + 1.9 and 49 + 1.7); at average heights the difference is under 1 kg.
Can children use this tool?
No. The formulas and WHO’s adult BMI cut-offs are for adults; for ages 5 to 19, WHO reads BMI against its growth reference for age and sex.
Source
- McCarron MM, Devine BJ. Case number 25: gentamicin therapy. Drug Intell Clin Pharm 1974;8(11):650–5 (Devine formula)
- Robinson JD et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm 1983;40(6):1016–9, abstract (coefficients)
- Miller DR, Carlson JD, Lloyd BJ, Day BJ. Determining ideal body weight (and mass). Am J Hosp Pharm 1983;40(10):1622–5
- Peterson CM et al. Am J Clin Nutr 2016;103(5):1197–203, Table 3: Hamwi (1964), Devine, Robinson and Miller equations
- Pai MP, Paloucek FP. The origin of the “ideal” body weight equations. Ann Pharmacother 2000;34(9):1066–9 (review of origins)
- WHO Technical Report Series 894 (2000): Obesity — preventing and managing the global epidemic, Table 2.1 (p. 9)
- NIST SP 811, Appendix B.8: inch = 2.54 cm (exact), pound = 0.4535924 kg
- WHO, Growth reference data for 5–19 years (2007): BMI-for-age (5–19 years), BMI reference by age and sex