BSA Glossary: Mosteller, DuBois, Haycock & Dosing Terms

July 14, 2026

Why This Vocabulary Matters

Body surface area shows up across oncology, pediatrics, cardiology, and burn medicine, each with its own related terminology. This glossary defines the terms you’ll encounter using the BSA calculator, so a result like “1.82 m² (Mosteller)” is fully understandable in context.

Body Surface Area (BSA)

BSA is an estimate of the total external surface area of the human body, calculated from height and weight rather than measured directly. It’s used to scale medication doses, physiological measurements, and clinical indices more precisely than body weight alone, since surface area correlates more closely with metabolic rate and drug clearance for many drugs than weight does.

Mosteller Formula

The Mosteller formula — BSA = √((height cm × weight kg) ÷ 3600) — is the most widely used BSA formula in current clinical practice due to its simplicity and strong validation, especially for chemotherapy dosing. See the BSA calculator for automatic calculation.

DuBois & DuBois Formula

The DuBois & DuBois formula — BSA = 0.007184 × height^0.725 × weight^0.425 — was published in 1916 and is the original widely used BSA equation. It remains in clinical use today, often permitted as an alternative to Mosteller as long as it doesn’t produce more than a stated percentage dosing difference for the same patient.

Haycock Formula

The Haycock formula — BSA = 0.024265 × height^0.3964 × weight^0.5378 — is often specifically preferred in pediatric settings, since it was validated including smaller body sizes where Mosteller and DuBois can diverge more from measured values. See BSA for pediatric dosing for more detail.

mg/m² Dosing

mg/m² dosing expresses a medication dose per square meter of body surface area rather than per kilogram of weight or as a flat dose. Multiplying the mg/m² figure by a patient’s calculated BSA gives the total dose — this is the standard convention for most chemotherapy regimens. See BSA for chemotherapy dosing.

BSA Capping

BSA capping is the clinical practice of calculating a chemotherapy dose as if a patient’s BSA were no higher than a fixed ceiling (commonly 2.0 m² or 2.2 m²), even if their actual calculated BSA is higher. The intent is reducing toxicity risk in larger patients, though research — including a study published via the NIH’s PubMed Central archive — has questioned whether capping actually improves outcomes uniformly across all cytotoxic drugs, making it a debated and institution-specific practice rather than a universal rule.

Cardiac Index

Cardiac index is cardiac output (the volume of blood the heart pumps per minute) divided by BSA, used in cardiology to normalize heart function measurements across patients of different body sizes — the same underlying principle as BSA-based drug dosing, applied to a physiological measurement instead of a medication dose.

Total Body Surface Area (%TBSA)

%TBSA is a related but distinct concept used in burn medicine — the percentage of a patient’s total body surface area affected by burns, typically estimated with methods like the Rule of Nines rather than the height/weight BSA formulas covered by this calculator. It shares the underlying “body surface area” concept but uses different estimation tools.

Putting the Terms Together

Once you know the difference between the three formulas and understand what mg/m² dosing means, a result from the BSA calculator is fully interpretable. See common BSA calculation mistakes for the errors that most often affect real BSA-based calculations.