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Calculates Ideal Body Weight using the Devine formula.
Clinical decision-support tool for qualified healthcare professionals. Results are not a diagnosis and should not replace professional clinical judgment.
Ideal body weight is a reference weight estimate most often used to guide medication dosing and nutritional assessment. The Devine formula was derived for aminoglycoside dosing in adults and does not account for body composition or frame size; actual body weight may be more appropriate for certain drugs and clinical situations.
Specialty
Internal MedicineCategory
Internal MedicineDifficulty
Basic
Estimated Time
30 seconds
Version
1.0
Last Updated
2026-07
Formula
Keywords
Estimates ideal body weight using the Devine formula, providing a size-adjusted reference weight used in drug dosing and physiological comparisons.
Ideal body weight uses the Devine formula: for males IBW (kg) = 50 + 2.3 x (height in inches - 60); for females IBW (kg) = 45.5 + 2.3 x (height in inches - 60), where inches = height (cm) / 2.54.
Biological sex, which sets the base weight (50 kg for males, 45.5 kg for females).
Height in centimeters, converted to inches (cm / 2.54) for the Devine formula.
IBW provides a reference weight for a given height and sex; it does not define health or body composition. It is commonly used as the weight basis for certain drug-dosing calculations and for deriving adjusted body weight.
IBW is the foundation for several weight-based dosing adjustments, particularly adjusted body weight in obese patients, and is widely used in clinical pharmacy and dosing practice.
A 35-year-old man is 180 cm tall.
Inputs:
Expected Result: IBW = 50 + 2.3 × (180/2.54 − 60) ≈ 75.0 kg using the Devine formula.
Ideal body weight is a height- and sex-based reference weight used to guide medication dosing and to derive adjusted body weight in patients above their ideal weight. The Devine equation behind this calculator was originally developed for aminoglycoside dosing in adults. It does not account for body composition or frame size, and for some drugs actual body weight may be the more appropriate dosing weight, so drug-specific guidance should always be checked.
The Devine formula starts from a different constant for each sex: males begin at 50 kg and females at 45.5 kg, and the same 2.3 kg is then added or subtracted per inch away from 60 inches of height. Choosing the wrong sex option therefore shifts the whole result, which matters because this value feeds into weight-based dosing calculations.
No. The Devine equation was derived for adults and has not been validated in children, who need age- and height-based references instead. Ideal body weight is also only a mathematical reference rather than a measure of health, and competing equations such as Robinson, Miller, and Hamwi give different values for the same patient, so the same formula should be used consistently when results are compared.
Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Ideal body weight is an estimate and dosing decisions must follow drug-specific guidance.