1BSA Formulas Explained
DuBois: BSA = 0.007184 × Height^0.725 × Weight^0.425
Boyd: BSA = 0.0003207 × Height^0.3 × Weight^(0.7285 - 0.0188×log10(Weight))
Haycock (paediatric): BSA = 0.024265 × Height^0.3964 × Weight^0.5378
Which Formula to Use?
Mosteller is the most widely used in clinical practice and oncology because of its simplicity (simple square root formula, easy mental math) and validated accuracy. Most chemotherapy dose calculation software uses Mosteller.
DuBois & DuBois (1916) was the original formula, derived from only 9 subjects, and may underestimate BSA in obese patients. Historically used for cardiac index calculation.
Haycock was specifically validated in children from neonates to adults and is the formula of choice for paediatric BSA calculations and paediatric eGFR normalisation.
Clinical Uses of BSA
- Chemotherapy dosing: Most cytotoxic drugs are dosed in mg/m² — carboplatin, doxorubicin, vincristine, paclitaxel. BSA capping at 2.0 m² is common practice to prevent toxicity in obese patients
- Cardiac index (CI): CI = Cardiac Output ÷ BSA. Normal CI = 2.5–4.0 L/min/m². Low CI (<2.2) indicates cardiogenic shock
- eGFR normalisation: CKD-EPI and MDRD give eGFR normalised to 1.73 m² BSA. Multiply by (patient BSA ÷ 1.73) to get absolute GFR in mL/min
- Radiation therapy: BSA used to plan radiation fields and calculate mean doses
BSA Capping in Chemotherapy
In obese patients, using actual BSA for chemotherapy dosing can lead to severe toxicity. Common capping strategies: cap BSA at 2.0 m² (most common), use IBW-based BSA instead of actual weight, or cap dose at standard adult dose. Always check the specific protocol — some regimens (e.g. carboplatin AUC-based dosing) use Calvert formula rather than BSA.
Conversely, underdosing based on capped BSA in obese patients may compromise chemotherapy efficacy. ASCO guidelines recommend using actual body weight (and hence actual BSA) for most chemotherapy regimens in obese patients with performance status.
2Frequently Asked Questions
Body Surface Area (BSA) calculations—most notably via the Mosteller formula—are essential in clinical practice for standardising chemotherapy dosing, cardiac index evaluations, and physiological metric normalisations.
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Medical disclaimer: This calculator is for educational and clinical decision-support purposes only. It does not replace clinical judgment or specialist consultation. RxMedCalc is not liable for clinical decisions made solely on this tool.