What is ideal body weight?
Ideal body weight, often shortened to IBW, is an estimate of a healthy weight for your height and sex. This ideal weight calculator works it out with the four best-known formulas, Devine, Robinson, Miller and Hamwi, and shows the healthy BMI range for your height next to them. The formulas give a single weight each, while the BMI range shows how wide a healthy weight can be. Together they give you a fair picture, not a target you have to hit.
The formulas
All four start from a base weight at 5 feet (60 inches) and add a fixed amount for every inch above that. The results are in kilograms. In the table, h is your height in inches minus 60.
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 + 2.3 × h kg | 45.5 + 2.3 × h kg |
| Robinson (1983) | 52 + 1.9 × h kg | 49 + 1.7 × h kg |
| Miller (1983) | 56.2 + 1.41 × h kg | 53.1 + 1.36 × h kg |
| Hamwi (1964) | 48 + 2.7 × h kg | 45.5 + 2.2 × h kg |
Example: a man who is 5 ft 10 in has h = 10. Devine gives 50 + 2.3 × 10 = 73.0 kg (161 lb), Robinson 71.0 kg (157 lb), Miller 70.3 kg (155 lb) and Hamwi 75.0 kg (165 lb). For a woman who is 5 ft 4 in, h = 4, the results are 54.7 kg with Devine, 55.8 kg with Robinson, 58.5 kg with Miller and 54.3 kg with Hamwi, or about 120 to 129 lb.
The healthy BMI range is the weight that gives a body mass index from 18.5 to 24.9 at your height: height in meters squared, times 18.5 and times 24.9.
Where the formulas come from
The Hamwi formula dates from 1964 and was meant as a quick rule for planning diets, especially for people with diabetes. The Devine formula followed in 1974, written to work out doses of certain drugs whose dose depends on body size rather than actual weight. It is still the formula most often used in hospitals for that purpose. Robinson and Miller published their versions in 1983, as adjustments of Devine based on weight tables of the time. None of them was designed to tell a person what they should weigh.
Limits of ideal weight formulas
- Frame size is ignored. People with a broad build weigh more at the same height without being less healthy.
- Muscle counts as weight. Athletes and people who lift weights often sit above every formula with little body fat.
- Age and body shape are ignored. Body composition changes with age, and where you carry fat matters more than the number on the scale.
- Short and very tall heights fit poorly. The formulas were made for adults 5 feet and taller, so below 5 feet this tool shows only the healthy BMI range.
If you are thinking about losing or gaining weight, a doctor or dietitian can help you find a goal that fits your body and health. This tool is for information, not medical advice.
How to use the ideal weight calculator
- 1Choose US or metric units and your sex. The formulas differ for men and women.
- 2Enter your height. Add your current weight if you want to compare.
- 3Read the ideal weight from each formula, the healthy BMI range and the chart. Copy the result or a link to it.
Frequently asked questions
Which ideal weight formula is the most accurate?
None of them is accurate for an individual. They were built as quick estimates, mainly for medication doses, and they give similar results for average heights. The Devine formula is the one most often used in hospitals. Looking at the range across all four, together with the healthy BMI range, is more useful than trusting a single number.
What is the ideal weight for a man who is 5 ft 10 in?
The four formulas give between about 155 and 165 lb (70.3 to 75 kg): Devine 161 lb, Robinson 157 lb, Miller 155 lb and Hamwi 165 lb. The healthy BMI range for that height is much wider, about 129 to 174 lb.
Why is the healthy BMI range so much wider than the formulas?
The formulas each give one number for a height, while the BMI range covers every weight with a BMI from 18.5 to 24.9, the range linked with the lowest health risks for most adults. People with a larger frame or more muscle are often healthy near the top of that range, or even above it.
Do these formulas work for people under 5 feet?
Not well. All four were made for people 5 feet and taller, and they start from a fixed weight at exactly 5 feet. Below that height the calculator shows only the healthy BMI range, which works for any adult height.
Should I aim for my ideal body weight?
Not necessarily. Your health depends on much more than weight, such as fitness, diet, sleep, blood pressure and where you carry fat. If you want to change your weight, talk to a doctor or dietitian about a target that fits you. This calculator is for information, not medical advice.