Formula & Calculator
Ideal Body Weight (Devine Formula)
Estimates a reference 'ideal' body weight for adults based on height, commonly used in clinical dosing calculations.
Interpretation
IBW(men) = 50 + 2.3×(height_in − 60); IBW(women) = 45.5 + 2.3×(height_in − 60). Estimates ideal weight for height. Used in clinical dosing and body composition assessment.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| IBW | Ideal body weight | kg |
| height_in | Height | inches |
What it means
The Devine formula estimates ideal body weight (IBW) based on height and sex. It was originally developed for drug dosing (e.g., for renal function estimation, anaesthesia). For men: 50 kg for 5 feet (60 inches) plus 2.3 kg per additional inch. For women: 45.5 kg for 5 feet plus 2.3 kg per additional inch. It is used in clinical nutrition, for ventilator settings, and in pharmacology to adjust doses. While it provides a reference, it does not account for muscle mass or body composition. Understanding IBW is useful for clinicians to estimate dosages and to set weight goals in obesity management.
Worked example
Ideal Body Weight (Devine) – Two Detailed Examples
Real‑World| Parameter | Value |
|---|---|
| Sex | Men |
| height (in) | 70 |
| Parameter | Value |
|---|---|
| Sex | Women |
| height (in) | 65 |
Common mistakes
- Devine formula: For men: 50 + 2.3 × (height_in − 60); for women: 45.5 + 2.3 × (height_in − 60).
- Height in inches: Not centimetres – convert if necessary.
- IBW: Ideal body weight – used for medication dosing and nutritional assessment.
- Limitations: Does not account for frame size or muscle mass – use with caution.
- Alternative formulas: Other formulas exist (Hamwi, Robinson) – choose the appropriate one.
Applications
The Devine formula provides estimates of ideal body weight (IBW) based on height and sex, commonly used in clinical settings for drug dosing and nutritional assessment. It is also used to set weight goals in weight management programmes. Healthcare professionals, such as physicians, dietitians, and pharmacists, use IBW to calculate appropriate medication doses, to assess nutritional status, and to guide weight recommendations. While it does not account for body composition, it is a quick and useful reference. By using IBW, clinicians can standardise dosage and monitor patient progress. Understanding IBW helps in the personalised management of obesity and related conditions.
- Drug dosage calculations (e.g., chemotherapy, anaesthesia)
- Nutritional assessment and diet planning
- Weight goal setting in obesity and eating disorders
- Clinical research and patient stratification
- Health promotion and lifestyle counselling
Frequently Asked Questions
It estimates a reference “ideal” body weight based on height, primarily used in clinical settings for medication dosing.
Men: 50 + 2.3 × (height_in − 60)
Women: 45.5 + 2.3 × (height_in − 60)
height_in = height in inches (multiply cm by 0.3937 to get inches). The constants 50 and 45.5 are the base weights for a 5‑foot (60‑inch) person.
Many drugs are dosed based on ideal body weight to avoid overdose in obese patients, where actual weight would give excessive doses.
- It was originally derived from insurance data, not from health outcomes.
- It does not account for frame size or muscle mass.
- It is not a health target; it is a dosing reference.
A woman who is 165 cm tall (≈65 inches) has IBW = 45.5 + 2.3 × (65−60) = 45.5 + 11.5 = 57.0 kg.
Adjusted body weight is used for dosing in obese patients and is calculated as (actual − IBW) × 0.25 + IBW.
It was based on a US population; other formulas may be better for different ethnic groups.
- Treating “ideal” body weight as a personal fitness goal – it is not; it is a dosing reference.
- Using the formula for children or adolescents.
- Using inches but forgetting to subtract 60.
Hamwi uses a slightly different base weight (men: 48 kg for first 152 cm; women: 45.5 kg for first 152 cm) and additional weight per inch. Devine is more commonly used in clinical practice.
Multiply kg by 2.20462.