Body Surface Area Calculator

Clinical BSA calculator with multiple formulas for medical dosing and assessments

🏥 CLINICAL USE ONLY: This calculator is intended for healthcare professionals. Always verify calculations and consider patient-specific factors. Not for self-medication or diagnosis. Follow institutional protocols for drug dosing.

Patient Information

Height

Height Unit

Weight

Weight Unit

Age (optional)

Gender (optional)

Calculation Options

BSA Formula

Clinical Context

Formula	Year	Best Applications	Accuracy
DuBois & DuBois The most widely used and accepted BSA formula in clinical practice	1916	General adult population Standard clinical calculations	Gold standard (±5% in normal weight adults)
Mosteller Simple and easy-to-calculate formula, commonly used in clinical practice	1987	Quick calculations Emergency settings	Very good (±3% compared to DuBois)
Haycock Specifically developed and validated for pediatric patients	1978	Pediatric patients Neonates and infants	Excellent for pediatrics (±2% in children)
Gehan & George Developed for cancer patients, particularly useful in oncology	1970	Cancer patients Chemotherapy dosing	Good for oncology patients (±4%)
Boyd Historical formula with good accuracy, less commonly used today	1935	Research applications Historical comparisons	Good (±5% in normal adults)
Fujimoto Developed for and validated in Japanese population	1968	Asian populations Japanese patients	Excellent for Japanese population (±3%)

Complete Guide to Body Surface Area Calculations

Understanding Body Surface Area in Medicine

Body Surface Area (BSA) is a critical measurement in clinical medicine, representing the total surface area of the human body. BSA calculations are essential for accurate medication dosing, particularly in oncology, pediatrics, and critical care, where precise dosing can mean the difference between therapeutic success and serious complications.

Unlike simple weight-based dosing, BSA accounts for both height and weight, providing a more accurate representation of metabolic mass and drug distribution. This is particularly important for chemotherapy agents, where therapeutic windows are narrow and toxicity risks are high. Our comprehensive calculator includes six validated formulas, each optimized for specific patient populations and clinical applications.

Major BSA Formulas

DuBois & DuBois (1916)
Gold standard formula, most widely used and validated
Mosteller (1987)
Simple square root formula, excellent for clinical use
Haycock (1978)
Specifically developed and validated for pediatric patients
Gehan & George (1970)
Developed for cancer patients and chemotherapy dosing

Critical Clinical Applications

Chemotherapy Dosing
Most cancer drugs dosed per m² for optimal efficacy and safety
Pediatric Medicine
Essential for safe drug dosing in children and neonates
Cardiac Index
Normalizing cardiac output to body size (CO/BSA)
Renal Function
eGFR indexed to standard BSA of 1.73 m²

Chemotherapy Dosing Guidelines

CRITICAL ONCOLOGY INFORMATION: Accurate BSA calculation is essential for safe chemotherapy administration. Dosing errors can result in treatment failure or life-threatening toxicity.

Standard Chemotherapy Agents

Agent	Standard Dose	Max Dose
Doxorubicin	60-75 mg/m²	Lifetime: 450-550 mg/m²
Cisplatin	75-100 mg/m²	Per cycle limit
Paclitaxel	175-200 mg/m²	Per infusion
Carboplatin	AUC 5-6	Based on Calvert formula

Special Dosing Considerations

Obesity Adjustments
Consider dose capping at BSA >2.0 m² for select agents
Pediatric Protocols
Use age-specific formulas and weight-based maximums
Organ Function
Adjust for hepatic/renal impairment independent of BSA
Performance Status
Consider dose reduction for poor performance status

Pediatric Body Surface Area Guidelines

Pediatric BSA calculations require special consideration due to the changing body proportions during growth and development. The Haycock formula is specifically validated for pediatric populations and provides the most accurate estimates for children and neonates.

Age Group	Typical BSA Range	Preferred Formula	Special Considerations
Neonates (0-28 days)	0.15-0.25 m²	Haycock	Rapid growth, frequent recalculation needed
Infants (1-12 months)	0.25-0.50 m²	Haycock	Weight changes rapidly with growth
Toddlers (1-3 years)	0.50-0.70 m²	Haycock	Activity level affects weight gain
School age (4-11 years)	0.70-1.20 m²	Haycock or DuBois	Growth spurts may occur
Adolescents (12-17 years)	1.20-1.80 m²	DuBois or Mosteller	Approaching adult proportions

Protocol Considerations: Pediatric oncology protocols often specify maximum doses regardless of BSA to prevent overdosing in larger children. Common practice includes dose modifications based on age, organ function, and protocol-specific guidelines.

Growth Monitoring: BSA should be recalculated regularly during treatment as children continue to grow. Significant changes in height or weight may require dose adjustments.

Safety Considerations: Pediatric patients may be more sensitive to certain chemotherapy agents. Age-specific toxicity profiles should always be considered alongside BSA calculations.

Formula Accuracy and Clinical Validation

Validation Studies

Each BSA formula has undergone extensive clinical validation in different patient populations. The accuracy of each formula varies based on patient characteristics, with most formulas showing ±3-5% agreement with direct measurement techniques.

DuBois Formula
Most extensively validated, considered gold standard
Mosteller Formula
Excellent correlation with DuBois, easier calculation
Haycock Formula
Superior accuracy in pediatric populations

Clinical Impact

The choice of BSA formula can impact calculated drug doses by up to 10% in some cases. For chemotherapy agents with narrow therapeutic windows, this difference can be clinically significant.

Best Practice: Use institution-approved formulas consistently and document which formula was used for dose calculations.

Formula Selection
Choose based on patient population and institutional guidelines
Documentation
Always document BSA value and formula used
Verification
Consider independent verification for high-risk medications

Special Population Considerations

Challenge: Standard BSA formulas may overestimate surface area in obese patients, potentially leading to overdosing. Many institutions implement dose-capping strategies for BSA values above 2.0-2.2 m².

Management Strategies:

• Consider dose capping for BSA >2.0 m² (varies by agent)
• Use adjusted body weight for certain calculations
• Monitor for enhanced toxicity in obese patients
• Follow institutional obesity dosing guidelines

Considerations: Elderly patients may have age-related changes in body composition, organ function, and drug metabolism that affect dosing decisions beyond BSA calculations.

• Reduced muscle mass may affect BSA accuracy
• Consider dose reduction for age ≥75 years
• Monitor for enhanced drug sensitivity
• Assess performance status and comorbidities

Fluid Balance Considerations: In critically ill patients, fluid retention and edema can significantly affect weight measurements, potentially altering BSA calculations.

• Use dry weight when possible for calculations
• Consider Mosteller formula for rapid calculations
• Monitor for drug accumulation in edematous patients
• Reassess BSA with significant weight changes

Quality Assurance and Best Practices

Accurate BSA calculations are critical for patient safety, particularly in oncology and pediatric medicine. Our calculator implements evidence-based formulas with built-in quality assurance features to ensure clinical accuracy.

Multiple Formula Validation
Compare results across different validated formulas
Clinical Context Awareness
Specialty-specific recommendations and guidelines
Pediatric Optimization
Age-appropriate formulas and reference ranges

Unit Conversion Safety
Automatic conversion between metric and imperial units
Calculation History
Track and review previous calculations for consistency
Professional Reporting
Generate clinical reports with formula documentation

Clinical Responsibility: This calculator provides decision support for healthcare professionals. Always verify calculations, consider patient-specific factors, and follow institutional protocols. Not intended for patient self-use or replacement of professional medical judgment.

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Drug Safety

Body Surface Area Calculator

Patient Information

Calculation Options

BSA Formula Comparison & Reference

DuBois & DuBois

Mosteller

Haycock

Gehan & George

Boyd

Fujimoto