Body surface area (BSA) is the total area of the body's outer surface, in square metres, estimated from height and weight. It matters in medicine because it scales with metabolism better than weight alone, so doses (especially chemotherapy) and indices like cardiac output are often expressed per m². The everyday formula is Mosteller: BSA = √(height × weight / 3600), with Du Bois as the historical standard. The average adult is about 1.7 m²; this tool reports both formulas and their average.
Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: the Mosteller and Du Bois BSA formulas. Not medical advice.
The BSA formulas
Mosteller is a neat square-root expression that is easy to compute by hand and accurate enough for clinical use, which is why most dosing references default to it. Du Bois, the original 1916 formula, raises height and weight to fixed powers; it gives very similar numbers across the normal range. Both increase with height and weight, so a taller, heavier body has a larger surface area. To convert to square feet, multiply the m² value by 10.7639.
Worked example — 180 cm, 80 kg
Scenario: an adult 180 cm tall weighing 80 kg.
Both formulas land at essentially 2.00 m² — about 21.5 square feet — and their close agreement is typical. BSA tracks body size smoothly: 160 cm / 60 kg gives about 1.63 m², 170 cm / 70 kg about 1.82 m², and 190 cm / 90 kg about 2.18 m². Against the adult average of roughly 1.7 m², this person is on the larger side. Because the two formulas rarely differ by more than a couple of percent, either is a sound estimate — but any clinical application must be done by a professional.
Frequently Asked Questions
Total body surface area in m², from height and weight. Average adult ≈ 1.7 m².
Mosteller √(ht×wt/3600) or Du Bois 0.007184×ht^0.725×wt^0.425. 180/80 → 2.00 m².
Mosteller is the popular default; Du Bois is the historical standard. They agree closely.
It tracks metabolism better than weight. Chemo and cardiac index use per-m². Clinicians only.
About 1.7 m² average; most adults 1.5–2.2 m². Rises with height and weight.