Body Surface Area (BSA) Calculator

Medical & Clinical Applications

Calculate body surface area using multiple scientific formulas including DuBois & DuBois, Mosteller, Haycock, Gehan & George, Boyd, and Fujimoto. Essential for drug dosing, burn assessment, and pediatric calculations.

Examples

Click on any example to load it into the calculator.

Adult Male

adultMale

A healthy adult male using the DuBois & DuBois formula for BSA calculation.

Formula: DuBois & DuBois

Gender: Male

Age: 35 years

Height: 175 cm

Weight: 75 kg

Adult Female

adultFemale

A healthy adult female using the Mosteller formula for BSA calculation.

Formula: Mosteller

Gender: Female

Age: 28 years

Height: 165 cm

Weight: 60 kg

Pediatric Patient

pediatric

A child using the Haycock formula, which is optimized for pediatric BSA calculations.

Formula: Haycock

Gender: Male

Age: 8 years

Height: 130 cm

Weight: 28 kg

Elderly Patient

elderly

An elderly patient using the Boyd formula, which accounts for age-related changes.

Formula: Boyd

Gender: Female

Age: 72 years

Height: 160 cm

Weight: 65 kg

Other Titles
Understanding Body Surface Area (BSA): A Comprehensive Guide
Learn about body surface area calculations, their medical applications, and the science behind different formulas.

What is Body Surface Area (BSA)?

  • Definition and Importance
  • Physiological Basis
  • Measurement Units
Body Surface Area (BSA) is the total surface area of the human body, measured in square meters (m²) or square feet (ft²). It represents the external surface area of the body and is a crucial parameter in medical calculations.
Physiological Significance
BSA is directly related to metabolic rate, heat exchange, and drug distribution throughout the body. Unlike body weight, BSA provides a more accurate measure of metabolic mass and is particularly important for drug dosing calculations.
Measurement Units
BSA is typically expressed in square meters (m²) in the metric system, with values ranging from approximately 0.2 m² for newborns to 2.5 m² for large adults. In the imperial system, it's measured in square feet (ft²).

Typical BSA Values

  • Average adult BSA: 1.7-1.9 m²
  • Pediatric BSA range: 0.2-1.5 m²
  • BSA increases with height and weight

Step-by-Step Guide to Using the BSA Calculator

  • Input Requirements
  • Formula Selection
  • Result Interpretation
Using the BSA calculator is straightforward but requires accurate measurements and appropriate formula selection based on your specific needs.
Required Measurements
You need your height in centimeters and weight in kilograms. For some formulas, age and gender are also required. Ensure measurements are taken without shoes and on an empty stomach for consistency.
Formula Selection
Choose the appropriate formula based on your age group and application. DuBois & DuBois is most commonly used, while Mosteller is simpler and often preferred for quick calculations.

Formula Recommendations

  • DuBois & DuBois: Most accurate for adults
  • Mosteller: Simple and widely used
  • Haycock: Optimized for pediatric patients

Real-World Applications of BSA Calculations

  • Drug Dosing
  • Burn Assessment
  • Pediatric Medicine
  • Oncology
BSA calculations are essential in numerous medical applications, providing more accurate dosing and assessment than weight-based calculations alone.
Drug Dosing
Many medications, especially chemotherapy drugs, are dosed based on BSA rather than body weight. This ensures more consistent drug levels and reduces toxicity risks.
Burn Assessment
The extent of burns is expressed as a percentage of total body surface area. Accurate BSA calculation is crucial for determining burn severity and treatment planning.

Common Medical Applications

  • Chemotherapy dosing: mg/m²
  • Burn assessment: % TBSA
  • Fluid resuscitation: mL/m²

Common Misconceptions and Correct Methods

  • Weight vs BSA
  • Formula Accuracy
  • Age Considerations
Several misconceptions exist about BSA calculations that can lead to errors in medical practice.
Weight-Based vs BSA-Based Dosing
Many people assume that drug dosing based on body weight is sufficient. However, BSA provides a more accurate measure of metabolic mass and is preferred for many medications.
Formula Selection
Not all BSA formulas are equally accurate for all populations. Pediatric patients, elderly individuals, and those with extreme body compositions may require specific formulas.

Key Considerations

  • BSA more accurate than weight for drug dosing
  • Different formulas for different age groups
  • Consider body composition for accuracy

Mathematical Derivation and Examples

  • DuBois & DuBois Formula
  • Mosteller Formula
  • Haycock Formula
  • Boyd Formula
The various BSA formulas are derived from statistical analysis of body measurements and provide different levels of accuracy for different populations.
DuBois & DuBois Formula
BSA = 0.007184 × weight^0.425 × height^0.725. This formula was developed in 1916 and remains the gold standard for adult BSA calculations.
Mosteller Formula
BSA = √(height × weight / 3600). This simplified formula is easier to calculate and provides good accuracy for most adults.
Haycock Formula
BSA = 0.024265 × weight^0.5378 × height^0.3964. This formula is optimized for pediatric patients and provides better accuracy for children.

Formula Characteristics

  • DuBois: Most accurate for adults
  • Mosteller: Simple and practical
  • Haycock: Best for pediatric patients