Body Surface Area (BSA) Calculator
Estimate total body surface area for medication dosing, fluid management, and clinical assessments using common medical formulas.
Patient Measurements
Enter height and weight in your preferred unit system.
Body Surface Area Estimates
Du Bois & Du Bois
1.81 m²
Classic formula, widely used for adult chemotherapy dosing.
Mosteller
1.818 m²
Simplified square root formula. Common in pediatrics.
Haycock
0.294 m²
Research-supported for infants and children.
Boyd
0.029 m²
Adjusts for weight using a logarithmic factor.
Converted measurements
Height: 1.70 m • Weight: 70.0 kg (154.3 lb)
How to Use This Calculator
Collect accurate measurements
Use a stadiometer for height and a calibrated scale for weight. Record values in metric or imperial units.
Compare formulas
Different hospitals prefer different BSA equations. Review all four estimates to align with your institution’s protocol.
Apply to clinical decisions
Use BSA to inform chemotherapy dosing, medication calculations, and metabolic assessments under professional guidance.
Formula
- Du Bois & Du Bois: BSA = 0.007184 × Height0.725 (cm) × Weight0.425 (kg)
- Mosteller: BSA = √((Height(cm) × Weight(kg)) ÷ 3600)
- Haycock: BSA = 0.024265 × Height(m)0.3964 × Weight(kg)0.5378
- Boyd: BSA = 0.0003207 × Height(cm)0.3 × Weight(kg)0.7285 − 0.0188 × log10(Weight)
All inputs are converted to metric before applying formulas. Results are presented in square meters (m²).
When to Use BSA
Body Surface Area correlates better with basal metabolic rate and organ size than simple weight-based dosing. Clinicians rely on BSA for chemotherapy, antibiotic dosing, burn treatment (to estimate affected surface), and pediatric fluid calculations.
Always cross-reference institutional protocols and patient-specific factors such as renal function, liver function, and comorbidities. BSA is a helpful reference, not a standalone dosing decision.
Frequently Asked Questions
Which formula should I trust?
Du Bois is the historical standard, Mosteller is common due to its simplicity, Haycock is ideal for pediatrics, and Boyd adjusts for weight extremes. Use the formula recommended by your clinical setting.
Can I use BSA for adults and children?
Yes. Some formulas perform better in certain populations (Haycock for pediatrics, Boyd for weight extremes). Compare them for context.
Does unit choice matter?
No. We convert height and weight to metric internally before calculation. Ensure both measurements use the same unit set.
How often should I recalculate BSA?
Recalculate when a patient’s weight changes substantially or before each chemotherapy cycle, following clinical guidelines.