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Simple Calculators

BSA Calculator

Body surface area by Mosteller and Du Bois — with optional mg/m² dose math

Patient Measurements

Clinical Disclaimer: This calculator is a decision-support tool only. BSA-based dosing must be verified independently, checked against the protocol and pharmacy, and administered per facility policy. Mosteller is the standard bedside formula; institutions may specify a different one.

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Quick summary

BSA estimates the body's surface area in square meters and drives dosing for chemotherapy and several other drug classes (ordered as mg/m²). The Mosteller formula — √(height cm × weight kg ÷ 3600) — is the bedside standard for its simplicity; Du Bois (1916) is the classic reference, and the two typically agree within a few percent. A 170 cm, 70 kg adult is about 1.82 m²; typical adult BSA is ~1.7 m².

Reviewed by Simple Calculators TeamLast reviewed

For information only — not medical advice. Results are estimates from published formulas and can't account for your health history. Talk to a doctor or other qualified clinician before making health decisions.

How to use this calculator

  1. Enter the inputs requested by the calculator.
  2. Choose the units or options that match your situation and review the assumptions.
  3. Run or update the calculation to see the result.
  4. Review the result, breakdown, and formulas shown on the page.
  5. Check the inputs, units, dates, and limitations before saving or sharing the result.

Frequently asked questions

What is the Mosteller formula?

BSA = √(height in cm × weight in kg ÷ 3600). Published in 1987 as a simplification that can be done on any calculator, it has become the default in most hospitals and EHRs. For 170 cm and 70 kg: √(11,900 ÷ 3,600) = √3.31 ≈ 1.82 m².

Why is chemotherapy dosed by BSA?

Drug clearance correlates better with body surface area than raw weight for many agents, a practice dating to the 1950s. An order like 'doxorubicin 60 mg/m²' multiplies by the patient's BSA — 60 × 1.82 = 109 mg. The optional dose field performs exactly this multiplication.

Mosteller vs Du Bois — which should I use?

They agree within roughly 2–3% for most adults. Mosteller is the modern bedside default; Du Bois remains embedded in older references and some protocols. Your institution's policy or the specific protocol dictates the choice — this calculator shows both so you can cross-check.

Is BSA dosing capped for larger patients?

Historically many protocols capped BSA at 2.0–2.2 m² out of toxicity caution, but ASCO guidance since 2012 recommends full-weight-based dosing for most adult chemotherapy, as capping underdoses larger patients without reducing toxicity. Follow the specific protocol and institutional policy — never a website.

Key terms

BSA
Body surface area in m² — the dosing basis for chemotherapy and several other drug classes.
mg/m²
Milligrams of drug per square meter of BSA — multiply by the patient's BSA for the absolute dose.
Mosteller Formula
√(cm × kg ÷ 3600) — the 1987 bedside standard.
Du Bois Formula
0.007184 × height^0.725 × weight^0.425 — the 1916 reference equation.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.