Adjusted Body Weight Calculator

Used when actual body weight markedly exceeds ideal body weight to avoid overdosing weight‑based therapies. Most often applied for drug dosing in obesity (e.g., antimicrobials, anticoagulants, select chemotherapy) and for estimating nutrition needs when excess adipose tissue would inflate requirements. Clinical utility is preventing inaccurate dosing or metabolic overestimation while still incorporating part of excess weight that contributes to drug distribution or energy expenditure.

Use ideal body weight plus 25% of the excess above ideal to avoid overestimating metabolically active mass (adjusted BW = IBW + 0.25 × [actual − ideal]). Key cautions: not validated for drug dosing in obesity, may misestimate needs in CKD or extreme body sizes, and can lead to under‑ or overdosing if used as a surrogate for true pharmacokinetic drivers 1 [Level III evidence].