Formula
Devine IBW: male = 50 + 2.3 × (height in inches − 60) kg; female = 45.5 + 2.3 × (height in inches − 60) kg. Adjusted weight = IBW + 0.4 × (actual weight − IBW). Percent of IBW = actual weight ÷ IBW × 100.
Adjusted body weight is a convention that combines an estimated ideal body weight with a portion of the difference between actual and ideal weight. The word “ideal” is the historical name of the equation, not a personal goal, a health judgment, or a recommended target. This calculator uses the Devine equations for IBW and a fixed adjustment factor of 0.4. It shows the intermediate IBW so the arithmetic is transparent instead of returning an unexplained single value.
Worked example
For a male formula at 70 inches and 100 kg, IBW is 50 + 2.3 × 10 = 73 kg. Adjusted weight is 73 + 0.4 × (100 − 73) = 83.8 kg. Actual weight is 100 ÷ 73 × 100 = 137.0% of IBW.
How to use this calculator
- Select the male or female coefficient set used by the historical formula.
- Enter actual weight in kilograms or pounds.
- Enter height in centimeters or choose feet and remaining inches.
- Select Calculate to see IBW, adjusted weight, and actual weight as a percentage of IBW.
When not to use this
Do not apply this tool to children, pregnancy, or situations where fluid accumulation, amputation, or unusual body composition makes height-and-weight estimates inappropriate. The historical equation has a five-foot baseline. For height below 60 inches, this implementation intentionally withholds the estimate and displays an explanatory note instead of extrapolating downward. The formula uses binary sex categories from its original formulation; these may not describe every person adequately. The calculator cannot determine which coefficient set is clinically appropriate.
Reference ranges
| Measure | Context |
|---|---|
| 100% of IBW | Actual weight equals the calculated IBW |
| Above 100% of IBW | Actual weight exceeds the calculated IBW |
| Adjustment factor | 0.4 is fixed in this tool; not universal |
These are mathematical descriptions, reference only. There is no universal healthy reference interval for adjusted weight or percent of Devine IBW. Adjusted weight is mainly considered when actual weight is well above IBW, and different applications can require different factors or a different approach altogether. The 0.4 convention is separate from Devine’s original IBW equation. If actual weight is at or below IBW, the arithmetic is shown with a warning about limited applicability. No drug dosing content or recommendation is provided.
References
Frequently asked questions
Is ideal body weight a weight-loss target?
No. It is a historical formula estimate based on height and sex coefficients. It does not define an individual’s best weight or overall health.
Why use the factor 0.4?
It is the fixed convention requested for this calculator. Appropriate adjustment factors vary by use; 0.4 is not a universal physiological constant.
What if height is below five feet?
The calculator withholds the result. It does not extrapolate the Devine equation below its five-foot baseline.
Are pounds and kilograms supported?
Yes. One pound equals 0.45359237 kilograms, and one inch equals 2.54 centimeters. Results are shown in both kg and lb.
Can the result be used to choose a dose?
This site provides no dosing guidance. The suitability of a body-weight convention requires professional assessment for its intended application.
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