Body Surface Area and Body Weight Calculator
Body surface area by Mosteller and Haycock, with ideal and adjusted body weight for weight-based dosing.
Patient
Sex
Changes ideal and adjusted body weight only.
How these are calculated
Body surface area
Mosteller1
BSA (m²) = √( height (cm) × weight (kg) ÷ 3600 )
Haycock2
BSA (m²) = 0.024265 × height (cm)0.3964 × weight (kg)0.5378
Ideal body weight (IBW)3
Males: IBW = 50 kg + 2.3 kg for each inch (2.54 cm) over 5 ft (152.4 cm)
Females: IBW = 45.5 kg + 2.3 kg for each inch (2.54 cm) over 5 ft (152.4 cm)
Females: IBW = 45.5 kg + 2.3 kg for each inch (2.54 cm) over 5 ft (152.4 cm)
Adjusted body weight (ABW)
ABW = IBW + 0.4 × (actual weight − IBW)
ABW has been recommended for dosing aminoglycosides in people with obesity, that is, when actual body weight is more than 25% above IBW.4,5
Sex: the IBW formula classifies patients as male or female, as it was derived. These terms may not reflect a patient's identity; assess each patient individually.
Rounding: body surface area is shown to two decimals and weights to one. Apply the medication's own dose-rounding and maximum-dose rules.
References
- Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317(17):1098. PubMed
- Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults. J Pediatr 1978;93(1):62-6. PubMed
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm 1974;8:650-5.
- Green B, Duffull SB. What is the best size descriptor to use for pharmacokinetic studies in the obese? Br J Clin Pharmacol 2004;58(2):119-33. PubMed
- Traynor AM, Nafziger AN, Bertino JS. Aminoglycoside dosing weight correction factors for patients of various body sizes. Antimicrob Agents Chemother 1995;39(2):545-8. PubMed
Nothing you enter is saved or sent anywhere. These estimates support, and never replace, clinical judgement.