Ideal body weight is estimated with formulas that start from a base weight at 5 ft and add a fixed amount for each inch above it. The most used, Devine's, is 50 kg + 2.3 kg per inch for men and 45.5 kg + 2.3 kg per inch for women — 121 lb for a woman of 5 ft 4 in and 161 lb for a man of 5 ft 10 in. The Robinson, Miller and Hamwi formulas give figures within a few pounds of it.
Enter your sex and height to see all four, the BMI each one lands on, and the healthy BMI weight range for your height — which, for everyday purposes, is the better guide.
Worked example
Sex: FemaleHeight: 5 ft 4 in
Ideal weight for a woman, 5 ft 4 in: 120–129 lb Inside the healthy BMI range
Devine’s formula, the one hospitals use, gives 121 lb (54.7 kg). All four formulas land inside the healthy BMI range at that height, 108 to 145 lb, and in its lower half.
Open this example in the calculator →How to use the Ideal Weight Calculator
- Choose your sex — each formula has separate versions for men and women.
- Choose US or metric units and enter your height.
- Read the ideal weight from each formula and the range they span.
- Compare them with the healthy BMI weight range for your height.
The ideal body weight formulas
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Robinson (1983) | 52 kg + 1.9 kg per inch | 49 kg + 1.7 kg per inch |
| Miller (1983) | 56.2 kg + 1.41 kg per inch | 53.1 kg + 1.36 kg per inch |
| Hamwi (1964) | 106 lb + 6 lb per inch (48 kg + 2.7 kg) | 100 lb + 5 lb per inch (45.5 kg + 2.2 kg) |
Worked through for a man of 5 ft 10 in (10 inches over 5 ft): Devine gives 50 + 23 = 73 kg (161 lb); Robinson, 71 kg (157 lb); Miller, 70.3 kg (155 lb); Hamwi, 75 kg (165 lb).
Where the formulas come from
Dr Ben Devine published his formula in 1974 in a paper on dosing the antibiotic gentamicin, as a quick way to estimate lean body size. It was not based on a study of what people should weigh, but it caught on and is still the standard in hospitals for drug doses, ventilator settings and estimating kidney function. Robinson and Miller each refitted it in 1983 to life-insurance height–weight tables; Hamwi's rule of thumb came from diabetes care a decade earlier.
Ideal weight by height
| Height | Women (Devine) | Men (Devine) | Healthy BMI range |
|---|---|---|---|
| 5 ft 0 in | 100 lb | 110 lb | 95–127 lb |
| 5 ft 2 in | 110 lb | 120 lb | 101–136 lb |
| 5 ft 4 in | 121 lb | 131 lb | 108–145 lb |
| 5 ft 6 in | 131 lb | 141 lb | 115–154 lb |
| 5 ft 8 in | 141 lb | 151 lb | 122–164 lb |
| 5 ft 10 in | 151 lb | 161 lb | 129–173 lb |
| 6 ft 0 in | 161 lb | 171 lb | 137–183 lb |
| 6 ft 2 in | 171 lb | 181 lb | 144–194 lb |
Limits of "ideal" weight
- It ignores build. Two people of the same height and sex get the same figure whatever their frame or muscle.
- It is linear. Each inch adds the same weight, while real body size grows faster than height. The formulas run low for tall people and are unreliable under 5 ft.
- It was never a health target. Being at your "ideal" weight is not known to be healthier than being anywhere else in the healthy BMI range.
For a target, the healthy weight range is the evidence-based answer, and the goal weight calculator shows how long it would take to get there.
Frequently asked questions
What is my ideal weight?
By the Devine formula: 45.5 kg plus 2.3 kg for each inch over 5 ft for women, 50 kg plus 2.3 kg per inch for men. That is 121 lb for a woman of 5 ft 4 in and 161 lb for a man of 5 ft 10 in. Any weight in the healthy BMI range is a healthy weight.
Which ideal weight formula is the most accurate?
None is accurate in the sense of predicting the healthiest weight for one person — none was designed to. Devine is the most used, in medicine, for drug dosing. Robinson and Miller fit insurance tables of their day slightly better. The healthy BMI range is the better guide for a target.
What is the ideal weight for a 5 ft 6 in woman?
About 131 lb by Devine, and 129 to 135 lb across the four formulas. The healthy BMI range at 5 ft 6 in is 115 to 154 lb.
What is the ideal weight for a 6 ft man?
About 171 lb (77.6 kg) by Devine, and 161 to 177 lb across the four formulas. The healthy BMI range at 6 ft is 137 to 183 lb.
Is ideal body weight the same as healthy weight?
No. Ideal body weight is one figure from a formula; a healthy weight is a range, from a BMI of 18.5 to 24.9. The formulas usually land in the lower half of that range.
Does frame size change my ideal weight?
Hamwi suggested subtracting 10% for a small frame and adding 10% for a large one. Frame is usually judged from wrist size or elbow breadth. The healthy BMI range already allows for different builds.
Sources
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm 1974;8:650–655 — Drug Intelligence & Clinical Pharmacy
- Robinson JD et al. Determination of ideal body weight for drug dosage calculations. Am J Hosp Pharm 1983;40:1016–1019 — American Journal of Hospital Pharmacy
- Miller DR et al. Determining ideal body weight (and mass). Am J Hosp Pharm 1983;40:1622–1625 — American Journal of Hospital Pharmacy
- Hamwi GJ. Therapy: changing dietary concepts. In: Diabetes Mellitus: Diagnosis and Treatment, 1964 — American Diabetes Association
- Adult BMI Categories — Centers for Disease Control and Prevention
- Obesity and overweight (fact sheet) — World Health Organization
For general information only — not a diagnosis or a substitute for advice from a doctor. How we calculate.