Adjusted Body Weight Calculator
Estimate ideal body weight (IBW) and adjusted body weight (ABW) for medication dosing, anesthesia, and nutrition planning. The calculator uses the Devine equation with a 40% correction factor.
Patient Information
Enter height and actual body weight, then choose sex and preferred measurement units.
Calculated Weights
Actual weight
95.0 kg (209.4 lb)
Ideal body weight
56.9 kg (125.5 lb)
Adjusted body weight
72.1 kg (159.1 lb)
Interpretation
Significant deviation from ideal body weight. Adjusted body weight helps avoid overestimation during dosing.
Height
165.0 cm • 5 ft 5.0 in
Weight difference vs. IBW
+38.1 kg (84.0 lb)
How to Use This Calculator
Measure height and weight
Use a stadiometer for standing height and a calibrated scale for actual body weight. Record the values using your preferred unit system.
Choose sex and units
Select female or male to apply the Devine ideal body weight formula. Toggle units if you need to switch between metric and imperial.
Review IBW and ABW
Use ideal body weight for lean dosing strategies and adjusted body weight when the patient exceeds IBW by more than 20%.
Formula
IBWDevine = Base + 2.3 × (Height in inches − 60)
Base = 50 kg for males, 45.5 kg for females. Converted to pounds by multiplying by 2.20462.
ABW = IBW + 0.4 × (Actual Weight − IBW)
Example: Female, 165 cm (65.0 in), 95 kg (209 lb)
IBW = 45.5 + 2.3 × (65 − 60) = 56.5 kg
ABW = 56.5 + 0.4 × (95 − 56.5) = 71.9 kg
When to Use Adjusted Body Weight
Adjusted body weight is commonly used when dosing certain medications (like aminoglycosides), planning parenteral nutrition, or estimating energy expenditure for individuals whose actual weight significantly exceeds their ideal body weight. Using actual weight alone can overestimate renal clearance or caloric needs, while ideal body weight may underestimate them. ABW offers a middle ground that better reflects lean mass plus a fraction of excess adipose tissue.
Always pair ABW with clinical judgement. Consider organ function, comorbidities, and local protocols when making dosing decisions. The calculator is a decision support tool—not a substitute for professional guidance.
Frequently Asked Questions
Why use a 40% correction factor?
The 40% factor is widely adopted to account for the partial contribution of adipose tissue to pharmacokinetics. Some institutions may use 30% or 20% depending on the drug—always follow local protocols.
What if actual weight is below ideal body weight?
When actual weight is below IBW, dosing usually relies on the actual weight. The calculator returns the actual weight as ABW in that scenario.
Can I use this calculator for children?
No. The Devine equation was validated for adults. Pediatric dosing relies on age-specific formulas and body surface area.
Does sex include non-binary options?
The formula requires choosing the coefficient that corresponds to male or female reference data. Select the coefficient that best matches body composition for clinical decision-making.