Body Surface Area (BSA) Calculator
Calculate your body surface area (BSA) with the Mosteller and Du Bois formulas. Enter your height and weight to get your BSA in m², widely used for drug dosing and clinical measurements.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- For educational use. Clinical dosing must be done by qualified professionals.
Formula
Mosteller: BSA = √(height cm × weight kg ÷ 3600)
Du Bois: 0.007184 × height^0.725 × weight^0.425
- BSA estimates the external surface area of the body from height and weight.
- The Mosteller formula — √(height × weight ÷ 3600) — is the simplest and most widely used in practice.
- The Du Bois formula is an older standard and usually agrees with Mosteller within a few percent.
- BSA is used to dose chemotherapy and other drugs, and to index cardiac output and GFR.
- An average adult BSA is roughly 1.7 m²; values scale with body size.
170 cm, 70 kg
Inputs
- Height: 170 cm
- Weight: 70 kg
Mosteller BSA = √(170 × 70 ÷ 3600) ≈ 1.82 m², close to the Du Bois estimate.
Frequently asked questions
What is body surface area?
BSA is the total external surface area of the body, used in medicine to scale drug doses and physiological measurements to body size.
Which BSA formula should I use?
Mosteller is the most common because it is simple and accurate. Du Bois is a traditional alternative that gives very similar results.
Why is BSA used for drug dosing?
Many drugs, especially chemotherapy, are dosed per square metre of BSA because it tracks metabolic rate better than weight alone.
What is a normal BSA?
An average adult is around 1.6–2.0 m². Children are lower, scaling with their height and weight.
How accurate are these estimates?
They are well-validated population formulas, but for critical dosing clinicians confirm measurements and use professional judgement.
Related calculators
Cardiac Index Calculator Calculate cardiac index (CI) — cardiac output adjusted for body size. Enter cardiac output and body surface area, and this calculator divides one by the other to give CI in L/min/m², along with where it sits relative to the normal range. Cardiac Output Calculator Calculate cardiac output — the volume of blood your heart pumps each minute. Enter heart rate and stroke volume, and this calculator multiplies them (and converts to litres) to give cardiac output in L/min, with how it compares to the normal resting range. BMI Calculator Popular Calculate your Body Mass Index (BMI) from your height and weight and see which category it falls into. Enter your weight and height and this calculator returns your BMI, its category, and the healthy weight range for your height.