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BSA Calculator for Chemotherapy Dosing (2.0 m² Cap)
Chemotherapy is almost always prescribed per square metre of body surface area, so BSA (m²) is the number that sets the dose — which makes both the formula choice and the 2.0 m² capping convention matter. This calculator computes BSA by Mosteller (the bedside default) and shows Du Bois, Haycock, Gehan-George and Boyd alongside it, so you can see the spread before a dose depends on one value. A key clinical detail bare calculators omit: many chemotherapy protocols cap BSA at roughly 2.0 m² (or use a capped/adjusted BSA) for large patients, to avoid very high absolute doses and added toxicity without proven benefit. For 180 cm and 75 kg the BSA is about 1.94 m² by every formula — just under a typical 2.0 m² cap. Enter height and weight in metric or imperial units to compare all five formulas. This is an estimate — any chemotherapy or drug dose must be independently clinically verified against the drug protocol. Free, private, browser-only.
BSA (m²) sets per-m² chemotherapy and drug doses
- Many protocols cap BSA at ~2.0 m² (or use adjusted BSA) for large patients
- All five formulas shown so you see the spread before a dose depends on one
Frequently asked questions
Why do chemotherapy protocols cap BSA at 2.0 m²?
Because chemotherapy is dosed per m², dosing strictly by actual BSA gives very large patients very high absolute doses, with more toxicity but no proven benefit. Many protocols therefore cap BSA at roughly 2.0 m² or use an adjusted BSA. Whether and how to cap is protocol-specific — always check the drug protocol. It is an estimate, not dosing advice.
Does the BSA formula change the chemotherapy dose?
At average size the formulas agree to about 0.01 m², so the dose barely changes. At obesity or in pediatrics they diverge — Du Bois under-reads in obese patients, Haycock and Mosteller are favoured in infants — so the formula can shift the dose. This tool shows all five; use the formula and capping rule your protocol specifies and verify clinically.