Body Surface Area Calculator
Adjust the inputs below. Results update as you type.
How it works
BSA is used in drug dosing (especially chemotherapy), burn treatment, and cardiac output measurement. Mosteller formula: BSA = √(height(cm) × weight(kg) / 3600). Average adult BSA is approximately 1.7–1.9 m². Different formulas can vary by up to 5%—confirm which your clinical protocol requires.
Input guidance
- Use measured values (recent weight, height, activity level) rather than guesses.
- Recalculate every few weeks as your routine and body metrics change.
- Pair screening metrics with context such as sleep, stress, and medical history.
The formula
The Mosteller formula: BSA (m²) = √(height(cm) × weight(kg) ÷ 3600). It estimates total skin surface area, used in medicine for dosing.
Worked example
For 170 cm and 70 kg: BSA = √(170 × 70 ÷ 3600) = √3.31 ≈ 1.82 m².
More examples to test
- Maintenance case: keep activity constant and observe expected baseline ranges.
- Adjustment case: change only one major variable to understand sensitivity.
How to interpret results
Use results for awareness and planning, then validate with qualified medical or nutrition professionals for individualized decisions.
When this can be inaccurate
Population formulas cannot account for all biological factors such as medical conditions, medication effects, body composition differences, and genetics.
Change history
- July 2026: Quality-reviewed for publication with formula checks and explanatory copy updates.
Site-wide corrections also appear on the corrections log.
Track fitness goals with a top app
General wellness resource.
Frequently asked questions
Why is body surface area used in medicine?+
Many drug doses, especially chemotherapy, and physiological measures scale with BSA more accurately than with weight alone.
What is a typical BSA?+
Average adult BSA is roughly 1.7 m², with men generally higher than women. It rises with both height and weight.
Which formula is best?+
Mosteller is popular for its simplicity; Du Bois and Haycock are also common. They give very similar results for most people.
Can this calculator diagnose a condition?+
No. It is a screening and education tool only, not a clinical diagnosis.
When should I seek professional advice?+
Seek professional advice when results are extreme, persistent, or conflict with symptoms, goals, or prior medical guidance.