Body Surface Area Calculator - BSA Calculator

Body Surface Area Calculator - Calculate Your BSA

Calculate your body surface area (BSA) instantly with our free calculator. Compare results from multiple formulas including Mosteller, Du Bois, Haycock, and Boyd.

Calculate Your Body Surface Area

Your Measurements:

• Weight: [Input: kg/lbs]
• Height: [Input: cm/ft+in]

[Calculate Button]

Your Results:

• Mosteller BSA: [m²]
• Du Bois BSA: [m²]
• Haycock BSA: [m²]
• Boyd BSA: [m²]
• Average BSA: [m²]

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What is Body Surface Area?

Body Surface Area (BSA) is the measured or calculated surface area of a human body. It's an important measure in medicine for calculating drug dosages, estimating fluid requirements, and assessing burn severity.

Why BSA Matters

• Drug dosing: Many chemotherapy drugs are dosed based on BSA
• Fluid requirements: Used to calculate maintenance fluid needs
• Burn assessment: Used to determine burn severity and treatment
• Physiological normalization: Standardizes measurements across body sizes

BSA Formulas

Mosteller Formula (Most Common)

BSA = sqrt((height × weight) / 3600)

Where: height is in cm, weight is in kg

Advantages: Simple, accurate, widely used

Du Bois & Du Bois Formula

BSA = 0.007184 × (height^0.725) × (weight^0.425)

Where: height is in cm, weight is in kg

Advantages: Original standard formula, well-validated

Haycock Formula

BSA = 0.024265 × (height^0.3964) × (weight^0.5378)

Where: height is in cm, weight is in kg

Advantages: Accurate for children and adults

Boyd Formula

BSA = 0.0003207 × (height^0.3) × ((weight × 1000)^(0.7285 - (0.0188 × log10(weight × 1000))))

Where: height is in cm, weight is in grams

Advantages: Most accurate for all ages, especially infants

Typical BSA Values

Age Group	Average BSA	Range
Newborn	0.25 m²	0.20 - 0.30 m²
2 years	0.50 m²	0.42 - 0.58 m²
10 years	1.00 m²	0.85 - 1.15 m²
Adult	1.73 m²	1.50 - 2.00 m²

Uses of BSA in Medicine

Chemotherapy Dosing

Many cancer drugs are dosed based on BSA to ensure safe and effective treatment. This accounts for differences in body size while avoiding toxicity.

Burn Assessment

The "Rule of Nines" estimates BSA percentage affected by burns. This helps determine:

• Fluid resuscitation needs
• Transfer to burn center criteria
• Treatment intensity

Cardiovascular Measurements

BSA is used to normalize cardiac measurements:

• Cardiac index = Cardiac output ÷ BSA
• Stroke volume index

Which Formula Should You Use?

• Mosteller: Best all-around choice, simple and accurate
• Du Bois: Traditional choice, well-established
• Haycock: Good alternative for children
• Boyd: Most accurate for infants and very small children

What is the most accurate BSA formula?

The Mosteller formula is the most commonly used because it's simple and accurate for most purposes. The Boyd formula is considered most accurate for infants and very small children.

Why is BSA used for drug dosing?

BSA correlates better with metabolic processes than weight alone for certain drugs, especially chemotherapy agents. It helps standardize doses across different body sizes.

What is a normal BSA for adults?

The average adult BSA is approximately 1.73 m² for men and 1.60 m² for women. The normal range is typically 1.5 to 2.0 m².

How do I calculate BSA for children?

Use the same formulas with the child's height and weight. The Haycock or Boyd formulas are often preferred for pediatric patients as they may be more accurate for smaller bodies.

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