BSA Calculator
Calculate your body surface area (BSA) — used in clinical practice for drug dosing and assessing organ function — from your height and weight. The calculator shows results from the Mosteller, Du Bois, and Haycock formulas side by side.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
- All three formulas are mathematical approximations; no formula perfectly reflects true body surface area.
- Accuracy may vary for very obese, very lean, or paediatric patients.
Formula
Mosteller: BSA = √(height(cm) × weight(kg) / 3600)
Du Bois: BSA = 0.007184 × height(cm)^0.725 × weight(kg)^0.425
Haycock: BSA = 0.024265 × height(cm)^0.3964 × weight(kg)^0.5378
- Body surface area is the total area of the skin, a better basis for many drug doses than weight alone.
- The Mosteller formula — the square root of (height × weight ÷ 3600) — is the simplest and most widely used.
- Du Bois & Du Bois is the historical reference formula; Haycock is often favoured in paediatrics.
- All three use height in centimetres and weight in kilograms and give BSA in square metres.
- A typical adult BSA is around 1.7–1.9 m²; always confirm dosing calculations with a clinician.
170 cm, 70 kg adult
Inputs
- Weight: 70 kg
- Height: 170 cm
Mosteller BSA = √(170 × 70 ÷ 3600) = √3.306 ≈ 1.82 m², which sits in the typical adult range.
Frequently asked questions
What is body surface area used for?
BSA is used clinically to calculate drug doses (especially chemotherapy), cardiac index, and other measures that scale better with surface area than with weight.
Which BSA formula should I use?
Mosteller is the most common because it's simple and accurate. Du Bois is the classic reference, and Haycock is popular for children.
What units do I enter?
Enter height in centimetres and weight in kilograms. The result is given in square metres (m²).
What's a normal adult BSA?
Most adults fall between about 1.7 and 1.9 m², though this varies with body size.
Can I use this for dosing decisions?
No. It's an educational estimate. Any medication dose based on BSA must be verified by a qualified healthcare professional.
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