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Body Surface Area Calculator (Mosteller Formula)

Body surface area (BSA) estimates the skin-area scale of a person from height and weight. The Mosteller formula is BSA = √((cm × kg) / 3600) square meters. It is a clinical estimate used in some drug-dosing protocols. It is not a diagnosis, not your true measured surface, and not permission to dose medication.

cm
kg
lb
BSA (Mosteller)1.752 m²
Height used170 cm
Weight used65 kg

How this calculation works

Metric: plug height in centimeters and weight in kilograms into √((cm × kg)/3600).

Imperial: height feet and inches convert with 1 in = 2.54 cm; pounds with 1 lb = 0.45359237 kg, then the same formula.

A 180 cm, 80 kg adult gives √(14400/3600) = √4 = 2.00 m². A 170 cm, 65 kg adult is about 1.752 m².

Other formulas (Du Bois, Haycock) exist and disagree by a few percent. This page is Mosteller only. Oncology and pediatric dosing must follow the treating team’s protocol, not a website.

Worked example

170 cm and 65 kg → √(11050/3600) ≈ 1.752 m². 180 cm and 80 kg → 2.00 m² exactly on Mosteller.

Frequently asked questions

Why 3600?
Mosteller (1987) simplified earlier BSA equations into a geometric mean of height and weight scaled so typical adults land near 1.7–2.0 m². It is an empirical convenience, not a law of physics.
Can I use this to dose chemotherapy?
No. Dosing is a licensed-clinician task with protocol BSA rules, capping, and lab values. This is arithmetic only.
Is BSA better than BMI?
They answer different questions. BMI is kg/m² for weight status; BSA is m² for scaling some physiologic and pharmacologic quantities.
Children?
Mosteller is used in pediatrics in some protocols, but infant/neonate dosing is specialized. Do not treat this output as a pediatric order.
Amputations or edema?
Weight no longer tracks “usual” BSA. Clinical teams adjust. The formula will not.
Are inputs stored?
No. Browser only.
This tool is provided for general information only. Verify important figures independently. · Last reviewed: August 25, 2026