Body Surface Area Calculator

Calculate BSA using DuBois and Mosteller formulas from height and weight.

By Konstantin Iakovlev · Updated September 2026 · Source: Mosteller RD, N Engl J Med 1987 — Simplified calculation of body-surface area

Unit
Unit

BSA (DuBois)

1.95 m²

BSA (Mosteller)

1.95 m²

Body Surface Area

DuBois Formula1.948 m²
Mosteller Formula1.952 m²
Average Adult (1.7-1.9 m²)+8.2% vs avg

Use the Body Surface Area Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and is not medical advice. Results are estimates from standard formulas and the numbers you enter. Talk to a doctor or another qualified health professional about your own health before acting on them.

How It Works

Body Surface Area (BSA) estimates the total external area of the human body, and this tool computes it two ways, through the DuBois and the Mosteller formulas. Its main clinical use is dosing: most chemotherapy drugs are dosed per square meter of body surface area, so an error in BSA carries straight into the dose.

Two equations drive the result. The DuBois formula reads BSA = 0.007184 × Height(cm)^0.725 × Weight(kg)^0.425, while Mosteller takes the form BSA = √((Height(cm) × Weight(kg))/3600). Each approximates whole-body surface area and the two tend to land close to one another, with small differences. Mosteller's square-root version was published in 1987 as a simplified calculation (N Engl J Med 1987;317:1098); at the calculator's default of 70 inches and 170 lbs the two give 1.948 m² (DuBois) and 1.952 m² (Mosteller).

Enter height in inches or centimeters and weight in pounds or kilograms, and set each unit toggle to match; the calculator converts to centimeters and kilograms before applying the formulas. BSA is an approximation, and real physiology varies from person to person, so treat any figure here as a reference point. This tool serves information only; it does not replace a clinician, and any actual dosing or medical decision belongs in the hands of a qualified healthcare professional.

Example: BSA for a Child of 125 cm and 28 kg

  1. 1 A 7-year-old is 125 cm tall and weighs 28 kg. Set the height unit to cm and the weight unit to kg.
  2. 2 DuBois: 0.007184 × 125^0.725 × 28^0.425 = 0.007184 × 33.13 × 4.121 = 0.981 m².
  3. 3 Mosteller: √((125 × 28) ÷ 3600) = √(3500 ÷ 3600) = √0.9722 = 0.986 m². The calculator shows 0.98 and 0.99 m² in the summary and 0.981 and 0.986 m² in the breakdown.
  4. 4 The two formulas differ by about 0.005 m², roughly half a percent. An actual chemotherapy dose is set by the treating team from measured height and weight and the protocol's own rules; this example only shows the arithmetic.

Source: Mosteller RD, N Engl J Med 1987 — Simplified calculation of body-surface area · Last updated: September 2026

Frequently Asked Questions

Why is body surface area important in medicine?
Body surface area (BSA) is used mainly to calculate drug doses: most chemotherapy drugs are dosed per square meter of BSA. It is also used to scale other clinical measurements to body size.
How do you calculate body surface area?
The DuBois formula is BSA = 0.007184 x height(cm)^0.725 x weight(kg)^0.425. The Mosteller formula is simpler: BSA = sqrt((height(cm) x weight(kg)) / 3600). Both give results in square meters.
What is normal body surface area for an adult?
In a study of 3,613 adults receiving chemotherapy at three UK cancer centers in 2005, average BSA was 1.91 m² for men and 1.71 m² for women (1.79 m² overall). The calculator compares your DuBois result with 1.8 m².

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