Ideal & Adjusted Body Weight
Calculates Ideal Body Weight (Devine formula) and Adjusted Body Weight for use in drug dosing, ventilator settings, and nutrition.
Score interpretation
Actual weight within 10% of IBW. Use actual body weight for drug dosing.
→ Use actual body weight (ABW) for most drug dosing. Tidal volume in ventilation: 6–8 mL/kg IBW. Nutritional requirements based on ideal weight to avoid overfeeding.
Actual weight 10–30% above IBW. Adjusted Body Weight (ABW) = IBW + 0.4 × (ABW − IBW).
→ Use Adjusted Body Weight for: aminoglycosides, heparin, vancomycin, LMWH (if > 100 kg). Use IBW for: ventilator tidal volumes, many chemotherapy agents. Check individual drug dosing guidelines.
Significant obesity (> 30% above IBW). Drug dosing requires specialist calculation.
→ ABW = IBW + 0.4 × (total − IBW). Use IBW for ventilator settings (protective lung volumes). Use ABW for: renally dosed medications. Use total body weight for: propofol, succinylcholine loading dose, some chemotherapy. Always check individual drug SmPC or pharmacy review.
Interpretation bands for the IBW / ABW. Apply clinical judgement and local guidance.
References
- Devine BJ. Gentamicin therapy. Drug Intelligence and Clinical Pharmacy. 1974.
- Erstad BL. Dosing of medications in morbidly obese patients in the intensive care unit setting. Intensive Care Med. 2004.
Related
Curated clinical cross-links plus same-class fallbacks.
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022
- Hyperthyroidism Management · BTA / ETA 2018
- Adrenal Insufficiency · Society of Endocrinology / ESE 2016
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.