Body Surface Area Calculator

Body Surface Area Calculator

Clinically validated formulas for accurate BSA estimation

Measurements

Formula Selection

Different formulas are used in clinical practice, oncology dosing, and pediatric calculations.

Your Body Surface Area

Result shown in square meters (m²)

Body Surface Area (BSA) represents the total external surface area of the human body, expressed in square meters (m²). In clinical practice, BSA is widely used because it provides a more accurate physiological reference than body weight alone, especially when calculating medication dosages, chemotherapy dosing, cardiac output, renal function, and metabolic rates.

Unlike BMI, which only compares height and weight ratios, BSA reflects how body size impacts drug distribution and organ workload, making it a critical measurement in medical decision-making.

Why Body Surface Area Is Important in Healthcare

BSA is a standard measurement used across multiple medical specialties due to its clinical reliability:

  • Oncology: Chemotherapy dosages are frequently prescribed based on BSA to reduce toxicity risk.
  • Cardiology: Used to normalize cardiac output and stroke volume.
  • Nephrology: Helps assess kidney function and dialysis parameters.
  • Pediatrics: Essential for safe medication dosing in infants and children.
  • Anesthesiology: Supports anesthesia dose calculations.
  • Clinical Research: Standardizes patient size comparisons in trials.

Because of its broad clinical use, accurate BSA calculation is essential for patient safety.

How Body Surface Area Is Calculated

Body Surface Area cannot be measured directly in routine practice. Instead, it is estimated using validated mathematical formulas derived from population studies. These formulas use height and weight to approximate body surface.

This calculator supports multiple clinically accepted BSA formulas, allowing healthcare professionals and informed users to choose the most appropriate method.

BSA Calculation Formulas Explained

The Mosteller formula is the most commonly used method in modern clinical settings due to its simplicity and accuracy.

Formula:
BSA (m²) = √[(height × weight) / 3600]

Why it’s used:

  • Easy to calculate
  • Reliable for adults and children
  • Widely accepted in hospitals

2. Du Bois & Du Bois Formula

One of the earliest BSA formulas, still referenced in research.

Formula:
BSA = 0.007184 × height⁰·⁷²⁵ × weight⁰·⁴²⁵

Best for:

  • Historical comparisons
  • Research contexts

3. Haycock Formula

Often preferred in pediatric medicine.

Formula:
BSA = 0.024265 × height⁰·³⁹⁶⁴ × weight⁰·⁵³⁷⁸

Best for:

  • Infants and children
  • Pediatric dosing

4. Gehan and George Formula

Developed using regression analysis from clinical datasets.

Best for:

  • Clinical research
  • Oncology dosing references

5. Boyd Formula

Accounts for body mass in grams and logarithmic scaling.

Best for:

  • Extreme body sizes
  • Specialized research applications

Metric and Imperial Unit Support

This calculator supports both:

  • Metric units: centimeters (cm) and kilograms (kg)
  • Imperial units: inches (in) and pounds (lb)

Imperial values are automatically converted into metric units internally to ensure accurate medical calculations.

How to Use the Body Surface Area Calculator

  1. Select your preferred unit system (Metric or Imperial).
  2. Enter your height and weight.
  3. Choose the BSA formula appropriate for your use case.
  4. Click Calculate to instantly receive your BSA value in square meters (m²).

The result is displayed with precision suitable for clinical reference.

Interpreting Your BSA Result

Typical adult Body Surface Area values range between:

  • 1.6 – 1.9 m² for most adults
  • Lower values for children
  • Higher values for larger body frames

⚠️ Important:
BSA values should always be interpreted in clinical context. Medication dosing, especially chemotherapy or anesthesia, must be determined by a qualified healthcare professional.

Is This Calculator Clinically Reliable?

Yes. This calculator uses peer-reviewed, medically accepted formulas that are routinely used in hospitals, academic research, and pharmaceutical dosing guidelines.

However, this tool is intended for educational and informational purposes only and should not replace professional medical judgment.

Who Should Use a BSA Calculator?

  • Healthcare professionals
  • Medical students
  • Pharmacists
  • Researchers
  • Fitness and health analysts
  • Patients seeking to understand medical reports

Medical Disclaimer

This Body Surface Area Calculator does not provide medical advice. Always consult a licensed physician or healthcare provider before making medical or treatment decisions based on BSA values.

References & Clinical Standards

  • Mosteller RD. Simplified calculation of body-surface area. N Engl J Med.
  • Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known.
  • Haycock GB et al. Geometric method for measuring body surface area.

Frequently Asked Questions

What is Body Surface Area (BSA)? +
Body Surface Area (BSA) is the total external surface area of the human body, measured in square meters (m²). It is commonly used in medical settings to calculate medication dosages, especially in oncology, pediatrics, and cardiology.
Why is BSA used instead of body weight? +
BSA provides a more accurate representation of physiological size than body weight alone. It better reflects drug distribution, organ function, and metabolic activity, making it safer for medical dosing.
Which BSA formula is the most accurate? +
The Mosteller formula is widely recommended due to its balance of simplicity and accuracy. However, other formulas such as Haycock or Du Bois may be preferred in pediatric or research settings.
Is this BSA calculator suitable for children? +
Yes. This calculator includes formulas like Haycock and Mosteller, which are commonly used in pediatric medicine for safe and accurate dosing.
What unit is BSA measured in? +
Body Surface Area is measured in square meters (m²), which is the international standard used in clinical practice and medical literature.
Can I use this calculator for chemotherapy dosing? +
This calculator uses clinically accepted formulas; however, chemotherapy dosing must always be determined and verified by a licensed healthcare professional.