Ideal Weight CalculatorFree online fitness & health calculator — instant results, no sign-up
Ideal weight from four well-known formulas.
For general information only. This is not medical advice, diagnosis, dosing guidance or a treatment recommendation. Talk to a doctor or other qualified health professional about your health, pregnancy, or diet.
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How the result changes with height
Each row below was calculated with this tool, keeping every other input at its default and changing only height from half to one and a half times the default value. Use it to see how sensitive the answer is before you enter your own numbers.
| Height (cm) | Robinson | Miller | Devine |
|---|---|---|---|
| 88 | 3.8 kg | 20.5 kg | -8.3 kg |
| 131 | 36 kg | 44.3 kg | 30.6 kg |
| 175 (default) | 68.9 kg | 68.7 kg | 70.5 kg |
| 219 | 101.8 kg | 93.2 kg | 110.3 kg |
| 263 | 134.7 kg | 117.6 kg | 150.1 kg |
About the Ideal Weight Calculator
This calculator estimates ideal body weight (IBW) using four classic clinical formulas: Robinson, Miller, Devine, and Hamwi. These equations calculate expected weight based on biological sex and height in centimeters. Clinicians, researchers, and individuals use these benchmarks to gauge baseline weight estimates and guide medication dosing.
- Sex
- Biological sex (Male or Female), used to select formula-specific baseline weights and height coefficients.
- Height
- Total body height measured in centimeters, typically ranging from 120 cm to 220 cm.
Formula and method
inch = (h / 2.54) − 60 Robinson: Male = 52 + 1.9 × inch, Female = 49 + 1.7 × inch Miller: Male = 56.2 + 1.41 × inch, Female = 53.1 + 1.36 × inch Devine: Male = 50 + 2.3 × inch, Female = 45.5 + 2.3 × inch Hamwi: Male = 48 + 2.7 × inch, Female = 45.5 + 2.2 × inch
- hHeight in centimeters
- inchInches of height beyond 5 feet (60 inches)
Height is first converted from centimeters to inches, and the number of inches exceeding 5 feet (60 inches) is computed. Each of the four formulas applies a sex-specific base weight at 5 feet and adds or subtracts a fixed weight increment per extra inch. Final values are rounded to one decimal place and displayed in kilograms.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- SexMale
- Height175 cm
Results
- Robinson68.9 kg
- Miller68.7 kg
- Devine70.5 kg
- Hamwi72 kg
How to use the Ideal Weight Calculator
- 1Select your biological sex and enter your height in centimeters.
- 2Convert height to inches and subtract 60 inches to determine height above 5 feet.
- 3Evaluate each formula (Robinson, Miller, Devine, Hamwi) using the appropriate sex-specific constants.
- 4Review the resulting weight targets in kilograms rounded to one decimal place.
Reading your result
Each formula offers a slightly different estimate because they were derived from different historical study cohorts and clinical assumptions. Devine and Hamwi are standard benchmarks in clinical pharmacokinetics, whereas Robinson and Miller tend to yield narrower estimates for tall individuals. Together, the four values form a practical reference range rather than a single rigid target.
Limitations
These formulas only consider total height and sex, ignoring body composition, frame size, age, and lean muscle mass. They assume a linear scaling past 5 feet (152.4 cm) and can yield unrealistically low or negative estimates for individuals shorter than 5 feet.
Common questions
Why do the four formulas give different results?+
Each equation was established empirically for different populations and purposes. For example, the Hamwi formula was developed as a rule of thumb for diabetic nutrition, while the Devine formula was initially calibrated for drug clearance calculations.
Which formula is most widely used in medicine?+
The Devine formula is the most frequently cited in clinical settings, particularly for calculating renal drug dosages and ventilator tidal volumes.
What happens if my height is under 5 feet (152.4 cm)?+
Because the formulas compute inches above 5 feet, heights below 152.4 cm produce a negative inch value, subtracting weight from the 5-foot base. These formulas were not originally validated for adults under 5 feet.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.