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Body Surface Area Calculator

Body Surface Area (BSA) estimates the total area of the outer surface of your body in square meters. Unlike body weight alone, BSA accounts for both height and weight, making it a more accurate basis for drug dosing (especially chemotherapy), fluid resuscitation in burn patients, renal clearance calculations, and cardiac index measurements. The most widely used formula is the DuBois equation (1916), though the simplified Mosteller formula and the pediatric-friendly Haycock formula are also common in clinical practice.

Quick Answer

Average adult BSA ranges from 1.7 to 1.9 m². BSA is calculated from height and weight and is used in medicine for accurate drug dosing and clinical assessments.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

Enter your height and weight above to calculate your Body Surface Area.

How the Formula Works

  1. Measure your height in centimeters and weight in kilograms. Convert from imperial units if needed (height: total inches x 2.54; weight: lbs x 0.4536).

    H (cm), W (kg)

  2. Apply the DuBois formula: multiply the constant 0.007184 by height raised to the power 0.725, then by weight raised to the power 0.425.

    DuBois BSA = 0.007184 × H^0.725 × W^0.425

  3. Alternatively, use the Mosteller formula for a simpler calculation: take the square root of the product of height and weight divided by 3600.

    Mosteller BSA = √(H × W ÷ 3600)

  4. Or use the Haycock formula, which is often preferred for pediatric patients: multiply 0.024265 by height raised to 0.3964, then by weight raised to 0.5378.

    Haycock BSA = 0.024265 × H^0.3964 × W^0.5378

Methodology & Sources

Reviewed and updated April 5, 2026 · Prepared by GetHealthyCalculators Editorial Team

The DuBois formula (1916) was derived from direct surface area measurements of nine individuals using molds. Despite the small sample size, it has been extensively validated and remains the most cited BSA formula. The Mosteller formula (1987) is a simplified square-root approximation that produces nearly identical results and is easier to calculate at the bedside. The Haycock formula (1978) was specifically developed and validated in pediatric populations. All three formulas are accepted in clinical practice, though the DuBois formula is the default in most oncology dosing protocols.

References

  • DuBois D, DuBois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;17(6):863–871. · Archives of Internal Medicine
  • Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. · New England Journal of Medicine
  • Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults. J Pediatr. 1978;93(1):62–66. · The Journal of Pediatrics
  • Verbraecken J et al. Body surface area in normal-weight, overweight, and obese adults. A comparison study. Metabolism. 2006;55(4):515–524. · Metabolism

How to Interpret Your Results

BSA values are interpreted in the context of medication dosing and clinical assessment. The average adult BSA is approximately 1.7 to 1.9 m². Values below this range are common in smaller adults and children, while larger individuals may have BSA above 2.2 m². BSA is particularly important for chemotherapy dosing, where under- or over-dosing can have significant consequences. All three major formulas produce similar results for average-sized adults but may diverge for very small or very large individuals.

Below Average
0–1.7 — Body surface area is below the average adult range. Common in smaller adults and children.
Average
1.7–1.9 — Body surface area falls within the typical adult range (1.7–1.9 m²).
Above Average
1.9–2.2 — Body surface area is above the typical adult range. May require dose adjustments.
Large
2.2–4 — Significantly above average. Medication dosing caps may apply to prevent toxicity.

Limitations

  • BSA formulas are empirical approximations derived from limited sample sizes. The original DuBois study used only nine subjects.
  • All BSA formulas may be less accurate at extremes of body size (very small children, very obese adults, or amputees).
  • BSA-based drug dosing assumes a linear relationship between body size and drug clearance, which does not hold for all medications.
  • Different formulas can produce slightly different results for the same person, especially at extremes of height or weight. Clinical protocols should specify which formula to use.
  • BSA does not account for body composition (muscle vs. fat), age, or organ function, all of which affect drug metabolism.

Frequently Asked Questions

What is Body Surface Area (BSA)?
Body Surface Area (BSA) is an estimate of the total outer surface of your body, measured in square meters (m²). It is calculated from your height and weight using validated formulas. BSA is widely used in medicine for drug dosing (especially chemotherapy), burn assessment, renal clearance calculations, and cardiac index measurements.
Why is BSA used instead of body weight for drug dosing?
BSA correlates better with many physiological parameters than body weight alone, including metabolic rate, blood volume, cardiac output, and glomerular filtration rate. This makes BSA a more reliable basis for calculating safe and effective drug doses, particularly for medications with a narrow therapeutic window like chemotherapy agents.
Which BSA formula should I use?
The DuBois formula is the most widely cited and is the default in most oncology and clinical protocols. The Mosteller formula produces nearly identical results and is simpler to calculate. The Haycock formula was specifically validated for children and is often preferred in pediatric settings. For average-sized adults, all three formulas give very similar results.
What is the average BSA for adults?
The average adult BSA is approximately 1.7 to 1.9 m². Adult males typically have a BSA around 1.9 m², while adult females average around 1.6 to 1.7 m². These values vary based on height, weight, and body composition.
Can I use BSA to assess my health?
BSA is primarily a clinical measurement used in medical settings rather than a health indicator like BMI or body fat percentage. However, knowing your BSA can help you understand medication dosing decisions and have informed conversations with your healthcare provider. For body composition assessment, BMI, body fat percentage, or waist-to-height ratio are more appropriate.
How accurate are BSA calculators?
BSA formulas provide estimates that are generally within 5–10% of directly measured body surface area. The DuBois formula has been validated in thousands of subjects over more than a century. Accuracy decreases at extremes of body size. For clinical purposes, the precision is considered sufficient for drug dosing when combined with clinical judgment and therapeutic monitoring.

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