Body Surface Area Formulas Compared: Mosteller vs Du Bois

Editorial note: Prepared by the CheckBodyScore Editorial Team. Last updated: 2026-06-18. This article explains calculator methodology, limitations, and practical interpretation. It is educational and is not a substitute for medical, legal, military, or financial advice.
Health June 18, 2026

Body surface area, or BSA, estimates the outside surface of the body from height and weight. It is often used in medical dosing, physiology, renal indexing, cardiac indexing, and research calculations.

Quick takeaways
  • The Mosteller formula is simple: BSA = square root of height cm x weight kg / 3600.
  • The Du Bois formula is older and more complex, but still appears in medical references.
  • BSA is an estimate and should not be used for medication changes without clinician guidance.

Mosteller Formula

The Mosteller equation is popular because it is easy to calculate and performs well for many routine uses: BSA = sqrt((height in cm x weight in kg) / 3600).

Its simplicity makes it a strong fit for online calculators. Users can see exactly how height and weight affect the result, and the formula is less intimidating than exponent-based equations.

Du Bois Formula

The Du Bois formula uses exponents rather than a square root: BSA = 0.007184 x height(cm)^0.725 x weight(kg)^0.425. It has historical importance and is still referenced in clinical literature.

Because formulas can diverge at very small, very large, or unusual body sizes, clinicians may prefer a specific method for a specific dosing or indexing protocol.

Which Formula Should You Use?

For general education, Mosteller is clear and practical. For clinical workflows, use the formula requested by the protocol, medication label, institution, or clinician. When BSA affects dosage, the final decision should come from a qualified professional.

Use the BSA Calculator Open Medical Dosage Calculator

Sources and References

We use official, clinical, and primary-reference sources where possible, then translate the methodology into plain language for calculator users.