Body Surface Area Calculator – Medication Dosing Aid
Calculate body surface area (BSA) with multiple medical formulas and unit conversions.
How to Use
- Enter the patient's weight and choose kilograms or pounds.
- Enter the patient's height and choose centimeters or inches.
- Select the BSA formula you want to apply (Mosteller, Du Bois, or Haycock).
- Click Calculate to view the converted measurements and BSA estimates from every formula.
Why body surface area matters
Body surface area is a more reliable indicator of metabolic mass than weight alone. Clinicians use BSA to individualize chemotherapy dosing, calculate IV fluid requirements, set ventilator tidal volumes, and determine burn treatment plans.
Because the original Du Bois formula relied on a small sample of subjects, alternate equations such as Mosteller and Haycock emerged to improve accuracy across age groups and body types. Reviewing multiple formulas can help clinicians understand how sensitive a dosing decision is to the chosen method.
Selecting the right BSA formula
- Mosteller: The square-root shortcut that is easy to compute manually and in bedside calculators.
- Du Bois: Historically important and still referenced in some oncology protocols.
- Haycock: Frequently recommended for pediatric patients due to lower bias in children and infants.
When protocols specify a single formula, always follow the clinical standard of care. If no formula is mandated, comparing output from multiple methods offers a quick sensitivity analysis to confirm dosing safety.
Frequently Asked Questions
- Which BSA formula should I use for chemotherapy dosing?
- Follow institutional policies and the prescribing information for each drug. Many oncology centers default to the Mosteller formula, but some protocols mandate Du Bois or another method. Always verify the required formula before adjusting medication orders.
- How accurate are BSA calculations in people with obesity?
- BSA formulas were derived from limited sample sizes and may overestimate or underestimate medication needs in people with severe obesity. Consider alternative dosing strategies, capped BSA values, or consult pharmacy guidelines tailored to high body mass indexes.
- Do I need BSA for everyday fitness tracking?
- BSA is primarily a clinical measurement. For general wellness, body mass index (BMI), body fat percentage, or resting metabolic rate provide more practical insights.