Pediatric BSA Dose Calculator
Body surface area (BSA)-based dosing adjusts an adult reference dose proportionally for a child's smaller BSA. The standard formula is: Child dose = Adult dose x (Child BSA / 1.73), where 1.73 m2 is the reference adult BSA. Child BSA is estimated from height and weight using the Mosteller formula: BSA = sqrt(height cm x weight kg / 3,600). This method is most commonly applied to oncology agents, but the same proportional scaling principle is used wherever BSA-adjusted dosing is specified in drug labeling.
Pediatric BSA dose formula
BSA (m2) = sqrt(Height (cm) x Weight (kg) / 3,600)
Child dose = Adult dose x (BSA child / 1.73)
BSA is calculated using the Mosteller formula. The adult reference BSA of 1.73 m2 represents an average adult weighing approximately 70 kg with height 170 cm. The child dose scales linearly with BSA ratio.
BSA dosing considerations
- BSA-based dosing is standard for most chemotherapy agents, where toxic-to-therapeutic ratio is narrow and body size must be accounted for precisely.
- For obese patients, using actual body weight may over-calculate BSA; some protocols specify adjusted or ideal body weight.
- Neonates and very small infants may require additional adjustments beyond BSA scaling due to immature renal and hepatic function.
- Always consult the drug-specific prescribing information for whether BSA or weight-based dosing is recommended.
- Maximum dose caps may apply regardless of BSA calculation; verify with pharmacist or protocol.
Pediatric BSA dose calculator: frequently asked questions
Why use BSA-based dosing in pediatrics?
Body surface area (BSA) correlates more closely with several physiological parameters (cardiac output, renal function, metabolic rate) than body weight alone, particularly for chemotherapy and some other drugs. BSA-based dosing normalizes for metabolic differences across age groups.
How is BSA calculated?
Several formulas estimate BSA. The Mosteller formula is widely used: BSA (m2) = sqrt(height cm x weight kg / 3,600). The DuBois formula is BSA = 0.007184 x weight^0.425 x height^0.725. Both give similar results for most patients.
What is 1.73 m2 in the formula?
1.73 m2 is the accepted standard BSA for an average adult (approximately 70 kg, 170 cm). The formula scales from an adult reference dose to a pediatric dose proportionally by BSA: Child dose = Adult dose x (Child BSA / 1.73).
Is BSA dosing used for all pediatric drugs?
No. Many pediatric drugs are dosed by weight (mg/kg). BSA dosing is used primarily for chemotherapy agents, some biologics, and certain drugs where weight-based dosing is inadequate. Always check drug-specific prescribing information and institutional protocols.
Can this calculator be used for clinical patient care?
This tool is for educational and informational purposes only. Pediatric dosing requires assessment by a qualified healthcare professional using patient-specific pharmacokinetic data, drug-specific guidelines, and institutional protocols.
Official sources
- U.S. Food and Drug Administration: FDA Pediatric Drug Development.
- NIH National Library of Medicine: Pediatric Dosing (StatPearls).
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.