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Body Surface Area Calculator

Calculate BSA for medical dosing

Body Surface Area

1.95 m²

Method

Mosteller

Category

Average

Units
ft
in
lbs

Body Surface Area

1.95

m²

Method: Mosteller

BSA Category

Small
< 1.5 m²
AverageYour BSA
1.5 – 2.0 m²
Large
2.0 – 2.5 m²
Very Large
> 2.5 m²

Formula

BSA = √(Height × Weight / 3600)

Example Calculations

1BSA using Mosteller (178 cm, 77 kg)

Inputs

Height178 cm
Weight77 kg
MethodMosteller

Result

Body Surface Area1.95 m²

BSA = sqrt(178 × 77 / 3600) = sqrt(13706 / 3600) = sqrt(3.807) = 1.95 m². This is within the normal adult male range of 1.7-1.9 m².

2BSA using Haycock (165 cm, 60 kg)

Inputs

Height165 cm
Weight60 kg
MethodHaycock

Result

Body Surface Area1.66 m²

BSA = 0.024265 × 165^0.3964 × 60^0.5378 = 0.024265 × 10.85 × 8.89 = 1.66 m². The Haycock formula uses power-law exponents and is commonly used in pediatric dosing.

Frequently Asked Questions

Q

What is body surface area (BSA)?

Body Surface Area is the total surface area of the human body. It's used in medicine to calculate drug dosages, especially for chemotherapy, and to assess metabolic rate.

  • BSA is measured in square meters (m²) and averages 1.7–1.9 m² for adults
  • Critical for dosing chemotherapy drugs – even small errors can be toxic or ineffective
  • Also used to calculate cardiac index, renal function, and burn area assessment
  • BSA correlates more closely with organ size than body weight alone
Q

Which BSA formula is most accurate?

The Mosteller formula is the most commonly used and is considered accurate for most adults. Du Bois is the original formula, and Haycock is often used for children.

  • Mosteller (1987): simplest formula – √(height × weight / 3600), accurate within 2–3%
  • Du Bois (1916): original formula, still widely cited in medical literature
  • Haycock (1978): preferred for pediatric patients under 10 years of age
  • All three formulas agree within 5% for typical adult measurements
  • For obese patients (BMI > 40), adjusted BSA formulas may be more appropriate
FormulaYearBest For
Mosteller1987Adults (most common)
Du Bois1916Adults (original standard)
Haycock1978Pediatric patients
Q

Why is BSA important in medicine?

BSA is used to calculate appropriate drug dosages, especially for medications with narrow therapeutic windows like chemotherapy. It provides a more accurate dosing method than weight alone.

  • Chemotherapy drugs are dosed in mg/m² because toxicity is surface-area-dependent
  • A 10% error in BSA calculation can mean 10% over/underdosing of critical drugs
  • Cardiac output is normalized to BSA as the cardiac index (L/min/m²)
  • Normal cardiac index: 2.5–4.0 L/min/m² – requires accurate BSA
  • Glomerular filtration rate (GFR) is often adjusted to 1.73 m² standard BSA
Q

What is a normal BSA?

Average BSA for adults is approximately 1.7-1.9 m² for men and 1.6-1.8 m² for women. BSA varies with height and weight.

  • Average adult male (178 cm, 77 kg): BSA ≈ 1.95 m²
  • Average adult female (165 cm, 60 kg): BSA ≈ 1.66 m²
  • Newborn (50 cm, 3.5 kg): BSA ≈ 0.22 m²
  • Children (120 cm, 25 kg): BSA ≈ 0.92 m²
  • The standard reference BSA used in medicine is 1.73 m²

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Last Updated: Mar 13, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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