Body Surface Area (BSA) Dosing Calculator
Enter patient weight and height to compute BSA with the Du Bois formula; use the result to tailor medication dosing.
Patient Measurements
Provide metric values only. Leave fields blank to reset validation warnings.
Typical adult ranges: 40–120 kg.
Use centimeters for accuracy; convert inches before entering.
Du Bois formula · use this value to adjust chemotherapy or other weight-based dosing.
How to Use This Calculator
Enter the patient’s weight in kilograms and height in centimeters. Click Calculate or wait for the inputs to debounce; the BSA result updates automatically. Leave zero or blank inputs to trigger validation and review the messages in the alert box.
- Capture the most recent weight and height from the patient record.
- Verify units: convert pounds to kilograms and inches to centimeters before entering them.
- Use the computed BSA to scale medication dosing by multiplying the per-square-meter dose by this value.
Methodology
The calculator relies on the Du Bois formula for BSA: it raises height and weight to fractional powers, multiplies them by the constant 0.007184, and rounds the final value to two decimal places. This mirrors the formula used by the cited Medscape method, so the output matches published clinical references.
Results are estimates and intended to support clinical judgment; always consult a licensed provider for dosing decisions.
Glossary of Terms
- Weight (kg): The patient’s current mass in kilograms.
- Height (cm): The patient’s standing height in centimeters.
- BSA (m²): Body Surface Area calculated in square meters.
Sample calculation
For a 70 kg, 175 cm adult, the calculator returns 1.85 m² because 0.007184 × 1750.725 × 700.425 ≈ 1.85. This matches the worked example from the original guide.
Frequently Asked Questions
What is BSA used for?
Oncology and other specialties use BSA to scale drug doses because many medications correlate better with metabolic mass than with body weight alone.
Why prefer BSA over BMI?
Unlike BMI, BSA reflects the total skin surface, which aligns more closely with physiological processes that determine drug distribution.
How do I calculate BSA manually?
You can apply the Du Bois formula directly, but this calculator automates the power functions and rounding for you.
Can BSA be used for children?
Yes, BSA calculations are broadly applicable; some pediatric regimens adjust further for age, so consult dosing guidelines.
What if my patient’s measurements are in imperial units?
Convert pounds to kilograms and inches to centimeters before entering values to keep the formula accurate.