Body Surface Area Calculator

Calculate BSA using multiple formulas in real-time

BSA Calculator

Units:
cm
Enter your height in centimeters
kg
Enter your weight in kilograms

BSA Calculation Formulas

Mosteller Formula
BSA (m²) = √[ height (cm) × weight (kg) / 3600 ]

Simplest and most commonly used formula in medical practice.

Du Bois Formula
BSA (m²) = 0.007184 × height (cm)0.725 × weight (kg)0.425

One of the earliest and most referenced BSA formulas.

Haycock Formula
BSA (m²) = 0.024265 × height (cm)0.3964 × weight (kg)0.5378

Developed specifically for pediatric patients but applicable to all ages.

Gehan & George Formula
BSA (m²) = 0.0235 × height (cm)0.42246 × weight (kg)0.51456

Based on 3D body surface measurements, considered highly accurate.

Understanding Body Surface Area (BSA) and Its Medical Importance

What is Body Surface Area (BSA)?

Body Surface Area (BSA) is the measured or calculated surface area of a human body. It's a crucial measurement in medical practice because many physiological processes correlate better with body surface area than with body weight. BSA is used extensively for calculating medication dosages, fluid requirements, and for assessing metabolic mass.

How to Use This BSA Calculator

Our BSA calculator is designed to be simple yet powerful:

  1. Select your measurement system - Choose between metric (cm, kg) or imperial (inches, pounds) units using the toggle at the top of the calculator.
  2. Enter your height and weight - Input your measurements in the appropriate fields. The calculator works in real-time, so you'll see results immediately.
  3. View your BSA results - The calculator provides BSA values using four different formulas, plus an average for comprehensive assessment.
  4. Use advanced options (optional) - Toggle the advanced options to input additional information like age and gender for potential future enhancements.

Why BSA Matters in Healthcare

BSA is used in various medical contexts:

  • Drug Dosage Calculation: Many chemotherapy drugs, anesthetics, and other medications are dosed according to BSA to maximize efficacy while minimizing toxicity.
  • Renal Function Assessment: Glomerular filtration rate (GFR) is often normalized to BSA for accurate interpretation.
  • Burn Assessment: The "Rule of Nines" for estimating burn surface area is based on BSA percentages.
  • Cardiac Index: Cardiac output is frequently indexed to BSA to compare patients of different sizes.
  • Nutritional Assessment: Caloric requirements and metabolic rate are often calculated based on BSA.

Understanding the Different BSA Formulas

Our calculator uses four established formulas:

  • Mosteller: The most commonly used formula in clinical practice due to its simplicity and reliability.
  • Du Bois: One of the original BSA formulas, still widely referenced in medical literature.
  • Haycock: Particularly accurate for pediatric patients but applicable across all age groups.
  • Gehan & George: Based on 3D body surface measurements, considered one of the most accurate methods.

While these formulas typically produce similar results, slight variations can occur. The average of all four provides a comprehensive estimate.

Limitations and Considerations

While BSA is a valuable clinical tool, it's important to understand its limitations:

  • BSA formulas were developed primarily from Caucasian populations and may be less accurate for other ethnicities.
  • Extreme body types (very muscular or very obese individuals) may not fit standard BSA calculations perfectly.
  • BSA doesn't account for body composition differences (muscle vs. fat distribution).
  • For precise medical applications, always consult with healthcare professionals who can consider your individual circumstances.

This calculator is intended for educational and informational purposes and should not replace professional medical advice.