🏆 Medical-Grade Accuracy

BSA Calculator 2025

Calculate Body Surface Area instantly with our medically accurate, free BSA calculator using proven formulas trusted by healthcare professionals worldwide for chemotherapy dosing and medical assessments.

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Calculate Body Surface Area

Enter height and weight to get instant, medically accurate BSA results using multiple validated formulas

kg
cm

Your BSA Result

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Square Meters (m²)
Enter your details to calculate BSA

BSA Reference Values

Population Average BSA Range
Adult Men 1.9 m² 1.6-2.4 m²
Adult Women 1.6 m² 1.3-2.0 m²
Children (10y) 1.1 m² 0.9-1.3 m²
Infants (1y) 0.5 m² 0.4-0.6 m²
Reference Adult 1.73 m² Standard

📐 BSA Formulas

Du Bois (1916): BSA = 0.007184 × W⁰·⁴²⁵ × H⁰·⁷²⁵
Mosteller (1987): BSA = √[(H × W) / 3600]
Haycock (1978): BSA = 0.024265 × W⁰·⁵³⁷⁸ × H⁰·³⁹⁶⁴
Gehan & George (1970): BSA = 0.0235 × W⁰·⁵¹⁴⁵⁶ × H⁰·⁴²²⁴⁶
W = Weight (kg), H = Height (cm)

⚠️ Medical Disclaimer

This BSA calculator is for informational purposes only. Results should not replace professional medical advice. BSA calculations are critical for chemotherapy dosing and medical assessments. Always consult healthcare professionals for medical decisions and drug dosing.

Understanding Body Surface Area (BSA)

Comprehensive guide to Body Surface Area, medical applications, and everything you need to know about BSA calculations and clinical significance.

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What is Body Surface Area?

Body Surface Area (BSA) refers to the total area of your body's outer surface, measured in square meters (m²). BSA is a more accurate indicator of metabolic mass than body weight because it's less affected by abnormal adipose mass and better reflects physiological processes.

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Medical Applications

BSA is critical for determining chemotherapy dosages, calculating cardiac index, estimating glomerular filtration rate (GFR), and assessing burn severity. Many medications, particularly those with narrow therapeutic indexes, are dosed based on BSA for optimal safety and efficacy.

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BSA Formulas

Over 40 BSA formulas exist, with Du Bois (1916) being most widely used, Mosteller (1987) offering simplicity, Haycock (1978) validated for children, and Gehan & George (1970) based on extensive measurements. Each has specific advantages for different populations.

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Clinical Accuracy

BSA values can vary by as much as 0.5 m² for the standard adult physique, depending on the formula used. Such discrepancies can lead to significant variations in dosages of critical medications, making formula selection crucial for patient safety.

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Metabolic Relevance

BSA is often used in clinical purposes over body weight because it is a more accurate indicator of metabolic mass (the body's need for energy). It correlates better with physiological functions like cardiac output, renal clearance, and heat loss.

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Limitations & Considerations

BSA accuracy decreases at extremes of height and weight. It may overestimate in obesity due to altered body composition. The standard 1.73 m² reference value represents an average 70kg adult but may not apply to all populations or age groups.

Frequently Asked Questions

Everything you need to know about BSA calculation, medical applications, and clinical significance answered by medical experts.

What is a normal BSA range?

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Average BSA for adult men is 1.9 m² (range 1.6-2.4 m²) and for adult women is 1.6 m² (range 1.3-2.0 m²). The reference standard of 1.73 m² represents an average 70kg adult and is commonly used in medical calculations.

Which BSA formula is most accurate?

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The Du Bois formula is most widely used in clinical practice, while Mosteller is preferred for simplicity. Haycock is validated for children. The choice depends on the population and clinical application. All major formulas show good correlation but can vary by up to 0.5 m².

Why is BSA used for chemotherapy dosing?

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BSA correlates better with metabolic rate and drug clearance than body weight alone. This makes it more accurate for dosing medications with narrow therapeutic indexes like chemotherapy agents, where precise dosing is critical to maximize efficacy while minimizing toxicity.

Can BSA be used for children?

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Yes, BSA formulas can be used for children. The Haycock formula was specifically validated for infants, children, and adults. The Mosteller formula is also commonly used in pediatrics. However, age-specific considerations and formula selection are important for accuracy.

How does BSA relate to cardiac index?

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Cardiac index is calculated as cardiac output divided by BSA, providing a better approximation of effective cardiac output adjusted for body size. Normal cardiac index is 2.5-4.0 L/min/m², making BSA essential for cardiovascular assessments.

Are there limitations to BSA calculations?

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BSA becomes less accurate at extremes of height and weight, may overestimate in obesity, and shows variability between formulas. There's ongoing debate about BSA's relevance in personalized medicine. Some advocate for alternative approaches in certain clinical situations.