About this calculator
Body surface area is used in many clinical formulas and some medication protocols. This calculator uses the simple Mosteller equation from height and weight.
Uses the Mosteller body surface area equation: BSA = sqrt((height in cm × weight in kg) / 3600).
Source-mapped educational formula
Educational estimate only; not a diagnosis, prescription, or treatment plan.
Formula and method
BSA (m²) = √((height in cm × weight in kg) / 3600). Medication dosing may require a specific protocol, dose cap, or alternate method.
Limitations and when not to rely on this result
- Educational estimate only; not a diagnosis, prescription, or treatment plan.
- Result depends on accurate inputs and may not apply to complex medical situations.
- Use clinician judgment, local guidance, and urgent care pathways when symptoms are severe.
Frequently asked questions
What formula does this BSA calculator use? +
It uses the Mosteller formula: square root of height in cm times weight in kg divided by 3600.
Can this be used for chemotherapy dosing? +
It can provide a reference BSA, but chemotherapy dosing requires oncology protocol checks, dose limits, organ-function review, and clinician verification.
Is BSA different from BMI? +
Yes. BSA estimates body surface area, while BMI is a weight-for-height index. They are used for different purposes.
When is BSA less reliable? +
Edema, burns, amputation, pregnancy, very small infants, and extreme body size can make simple height/weight formulas less reliable.
Is this for adults only? +
The formula can be mathematically applied across ages, but pediatric and neonatal medication dosing must follow pediatric protocols.