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Body Surface Area Calculator

Calculate body surface area (BSA) using multiple validated formulas including Mosteller, DuBois, and Haycock methods. Essential for medical dosing, physiological assessments, and clinical calculations.

Patient Measurements

Medical Use Disclaimer

For clinical applications, always verify calculations and consult appropriate medical protocols. This calculator is for educational and reference purposes.

Body Surface Area Results

Body Surface Area (Mosteller)

1.845 m²

Most widely recommended formula

Input Summary
Weight: 70 kg (70 kg)
Height: 175 cm (175 cm)
Age: 30 years
Gender: male
BMI: 22.9 kg/m²
Expected Range: 1.9-2.2 m²

Assessment

BSA below expected range for Adult male (70-80 kg)

Average (All Methods)

1.708

m² surface area

Range

0.902-1.863

m² (min-max)



What is Body Surface Area Calculator?

Understanding Body Surface Area (BSA)

Body Surface Area (BSA) is the measured or calculated surface area of a human body. It's expressed in square meters (m²) and is widely used in medical settings for drug dosing, physiological assessments, and normalizing various parameters to account for differences in body size.

Why BSA Matters in Medicine

  • Drug Dosing: Many medications, especially chemotherapy drugs, are dosed based on BSA to account for metabolic differences
  • Physiological Normalization: Parameters like cardiac output and kidney function are normalized to BSA for comparison
  • Pediatric Care: Essential for weight-independent dosing in children where weight alone may not reflect metabolic capacity
  • Critical Care: Used in burn assessment, fluid resuscitation calculations, and nutrition planning
  • Research: Standardizes measurements across different body sizes in clinical studies

Common BSA Formulas

Mosteller Formula (Recommended)

BSA = √[(height × weight) / 3600]

Simple, accurate, and widely adopted. Easy to calculate and remember.

DuBois & DuBois Formula

BSA = 0.007184 × W^0.425 × H^0.725

Historical standard from 1916. Still widely referenced and used.

Haycock Formula

BSA = 0.024265 × W^0.5378 × H^0.3964

Particularly accurate for children and adolescents.

Boyd Formula

Complex logarithmic calculation

Mathematically sophisticated but more complex to calculate.

Clinical Applications

Chemotherapy Dosing: Most cancer drugs are dosed in mg/m² to reduce toxicity variation
Cardiac Index: Cardiac output normalized to BSA (normal: 2.5-4.0 L/min/m²)
Glomerular Filtration Rate: Kidney function normalized to 1.73 m² BSA
Burn Assessment: Burn area calculated as percentage of total BSA
Pediatric Dosing: Many pediatric medications dosed per m² BSA
Nutritional Assessment: Caloric and fluid requirements often based on BSA

Normal BSA Values

Adult Men: 1.9-2.2 m² (average 2.0 m²)
Adult Women: 1.6-1.9 m² (average 1.7 m²)
Adolescents: 1.3-1.8 m² (varies with growth)
Children: 0.8-1.3 m² (age-dependent)
Infants: 0.25-0.8 m² (rapid changes with growth)

Limitations and Considerations

  • Body Shape Assumptions: Formulas assume normal body proportions and may be less accurate in extreme obesity or severe malnutrition
  • Population Differences: Some formulas were developed on specific populations and may not apply universally
  • Age Effects: Accuracy may vary across different age groups, particularly in very young or elderly patients
  • Clinical Context: BSA is a guide, not an absolute rule; clinical judgment should always be applied
  • Maximum Doses: Many institutions cap doses even when BSA would suggest higher amounts

Best Practices

Accuracy: Ensure precise height and weight measurements
Verification: Double-check calculations, especially for high-risk medications
Institutional Protocols: Follow your institution's preferred formula and guidelines
Clinical Assessment: Consider patient factors beyond BSA (organ function, age, etc.)
Documentation: Record which formula was used for consistency


FAQ - Body Surface Area Calculator

The Mosteller formula is most widely recommended due to its simplicity and accuracy. It's the preferred method in many clinical guidelines. However, your institution may have specific preferences. The DuBois formula is also widely accepted and historically significant. For pediatric patients, the Haycock formula may be more accurate.