Ideal Weight Calculator
Compare ideal body weight from the Devine, Robinson, Miller and Hamwi formulas with the healthy BMI range for your height.
Tool guide
What this tool does
The Ideal Weight Calculator applies four published ideal body weight formulas for your height and sex and averages them, then shows the healthy BMI 18.5 to 24.9 weight range alongside. Adjust for small or large frame, and optionally compare the result with your current weight.
"How much should I weigh?" has no single answer, but clinicians have used height-based formulas for decades. They were never designed as aesthetic targets: Devine (1974) produced his equation to calculate drug doses, and Robinson and Miller (both 1983) refitted it to life-insurance and population data. Hamwi (1964) is a quick bedside rule. Seeing them together gives a sensible band rather than one magic number.
Each formula starts from a base weight at 5 feet (152.4 cm) and adds a fixed amount per inch above it. For a man, Devine is 50 kg + 2.3 kg per inch, Robinson 52 kg + 1.9 kg, Miller 56.2 kg + 1.41 kg and Hamwi 48 kg + 2.7 kg; women have lower bases. The tool also shows the weight range that gives a BMI between 18.5 and 24.9 at your height, which is the range most health services use.
How to use Ideal Weight Calculator
- Choose metric or imperial units and select your sex.
- Enter your height in centimetres, or feet and inches.
- Choose a body frame; this adjusts the Hamwi result by 10 percent either way, as Hamwi originally suggested.
- Read the average ideal weight and the spread between formulas.
- Compare it with the healthy BMI range shown in the second card.
- Turn on "Compare with my current weight" to see the difference from your present weight.
Tips for better results
- Treat the overlap between the formula range and the BMI range as a reasonable target zone.
- To judge frame size, wrap your thumb and middle finger around your wrist: overlapping suggests a small frame, a gap suggests a large one.
- Muscular people can sit above every formula and still be healthy; use a body fat estimate as well.
Common use cases
- Setting a long-term weight goal that is grounded in published formulas.
- Nursing and pharmacy students checking ideal body weight for dosing exercises.
- Comparing how different formulas treat very short or very tall people.
- Giving context to a BMI result by turning it into kilograms or pounds.
Common mistakes to avoid
- Treating the number as a precise target; even the four formulas disagree by several kilograms.
- Using the formulas below 5 feet, where they subtract weight per inch and become unreliable.
- Forgetting that ideal body weight in medicine is used for dosing and ventilation settings, not as a fitness goal.
Frequently asked questions
Which ideal weight formula is best?
None is best for everyone. Devine is the most widely used in clinical dosing; Robinson and Miller give slightly different curves that some studies found closer to population averages. The average of all four is a fair summary.
Why does the result change with sex?
Each formula has separate male and female bases because, at the same height, men on average carry more lean mass and bone.
What does the frame size setting do?
Hamwi suggested subtracting 10 percent for a small frame and adding 10 percent for a large one. The tool applies that adjustment only to the Hamwi result.
Is the healthy BMI range different from ideal weight?
Yes. The BMI range spans every weight between BMI 18.5 and 24.9 at your height, so it is broader. The formulas produce a single point estimate inside or near that range.
Feedback & suggestions
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