Ideal Weight Calculator
Compare four clinical ideal weight formulas side by side.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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This calculator runs four commonly cited clinical formulas simultaneously and shows you the results side by side. Here is how to get your estimate:
- Choose your height unit. Select feet and inches for the U.S. standard or centimeters for metric. The calculator converts internally.
- Select your sex. All four formulas use sex-specific constants because males and females have different bone structure and lean mass distributions.
- Enter your height. For imperial, enter feet and inches separately. For metric, enter your height in centimeters.
- Read the results. The main result shows the average of all four formulas. The breakdown below lists each formula individually plus the healthy weight range based on a BMI of 18.5 to 24.9.
Results update live as you type. Use Copy to grab the number or Share to send a pre-filled link.
About the Ideal Weight Formulas
The four formulas used here were all developed between 1964 and 1983 by physicians who needed quick estimates of appropriate drug dosing weights. They are not judgments of what a person "should" weigh for appearance, but rather clinical reference points that correlate with lean body mass at a given height.
The Devine formula (1974) is the most widely used in clinical settings, particularly for pharmacokinetic calculations. The Robinson formula (1983) is similar but tends to produce slightly lower estimates. The Miller formula (1983) was designed to account for a wider range of body frames. The Hamwi formula (1964) is one of the oldest and uses a different base weight with a larger increment per inch.
No single formula is "correct." The average of all four gives a reasonable central estimate. The healthy BMI weight range shown alongside the formulas is often the most practically useful reference for general health goals.
Frequently Asked Questions
Which ideal weight formula is most accurate?
No single formula is definitively more accurate than the others because they were developed for different clinical purposes, not as fitness goals. The Devine formula is the most commonly cited in medical literature for drug dosing. For general health purposes, the healthy BMI weight range (BMI 18.5 to 24.9) is usually the most evidence-based reference since it correlates with lower all-cause mortality across large population studies.
Why do the four formulas give different results?
Each formula was derived from different patient populations and uses slightly different base weights and increments per inch of height above 5 feet. Devine uses 2.3 kg per inch, Robinson uses 1.9 kg for males and 1.7 kg for females, Miller uses 1.41 kg, and Hamwi uses 2.7 kg for males. These differences reflect different assumptions about body composition and frame size across each study's population.
Do these formulas apply to athletes or very muscular people?
No. All four formulas were created for average body compositions and are based on height alone, with no account for muscle mass. A 6-foot male athlete with 15% body fat might weigh significantly more than the Devine formula suggests, but that excess weight is muscle, not fat. For athletes, lean body mass calculators and FFMI (Fat-Free Mass Index) are more relevant measures than any ideal weight formula.
What is the Hamwi method and where does it come from?
The Hamwi method was published by Dr. George Hamwi in 1964 in a textbook on diabetes management. It was one of the first standardized clinical formulas for estimating ideal body weight and became widely taught in nursing and dietitian training. The base weight is 48 kg for males and 45.5 kg for females at 5 feet, with 2.7 kg added per inch for males and 2.2 kg per inch for females. It tends to produce slightly higher estimates than the other three formulas for taller individuals.