Du Bois (1916)
Original formula
1.85m²
Scenario
BSA for Chemotherapy Dosing
Understand how body surface area (BSA) is used in chemotherapy drug dosing. Learn why BSA-based dosing is preferred for many cancer treatments.
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Your Details
cm
kg
Your BSA Results
Mosteller (1987)
Most common
1.84m²
Haycock (1978)
Pediatric use
1.85m²
m²
Average of all three formulas
BSA on Reference Scale
1.85 m²
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- 1.8
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- 2.5
Formula Comparison
BSA Reference Range: Average BSA is approximately 1.7 m² for men and 1.6 m² for women. Your average BSA of 1.85 m² is above average, which is common for taller or larger-framed individuals.
The formula
The formula
What BSA Measures
Body Surface Area (BSA) is a measurement of the total external surface area of the human body, expressed in square meters (m²). Unlike BMI, which assesses weight relative to height, BSA estimates the physical extent of the body surface — a metric that correlates closely with metabolic rate, blood volume, and cardiac output.
BSA is most commonly used in clinical medicine to calculate chemotherapy dosages, determine medication doses for drugs with narrow therapeutic windows, and normalize physiological indices such as cardiac index and glomerular filtration rate. Because BSA-based dosing scales drug delivery to a patient's size more precisely than weight alone, it is the standard of care in oncology and several other specialties.
The BSA Formulas
Three validated formulas are provided in this calculator. Each was derived from measurements of different populations, and while they produce similar results for most adults, minor differences are expected. The most widely used formula in current clinical practice is the Mosteller formula, valued for its simplicity.
Du Bois (1916)
BSA = 0.007184 × W0.425 × H0.725
Mosteller (1987)
BSA = √(W × H ÷ 3600)
Haycock (1978)
BSA = 0.024265 × W0.5378 × H0.3964
Where W = weight in kilograms, H = height in centimeters
Formula Source
Du Bois & Du Bois (1916) — A formula to estimate the approximate surface area if height and weight be known. Archives of Internal Medicine, 17, 863–871.
Reference URL: https://doi.org/10.1001/archinte.1916.00080130008002
Mosteller (1987) — Simplified calculation of body-surface area. New England Journal of Medicine, 317(17), 1098.
Reference URL: https://doi.org/10.1056/NEJM198707233170417
Haycock et al. (1978) — Geometric method for measuring body surface area: A height-weight formula validated in infants, children, and adults. The Journal of Pediatrics, 93(1), 62–66.
Last Verified: 2026-08-09
Worked Example
Consider an adult who weighs 70 kg and stands 175 cm tall. Applying each formula side by side:
Du Bois: 0.007184 × 700.425 × 1750.725 = 0.007184 × 6.08 × 42.29 ≈ 1.85 m²
Mosteller: √(70 × 175 ÷ 3600) = √(12,250 ÷ 3600) = √3.403 ≈ 1.84 m²
Haycock: 0.024265 × 700.5378 × 1750.3964 = 0.024265 × 9.82 × 7.75 ≈ 1.85 m²
All three formulas converge near 1.85 m² for this individual, which is a typical adult BSA value. The small variation between formulas (within 0.01 m² in this case) is clinically acceptable for most applications.
BSA Formula Comparison Table
| Formula | Equation | Typical Use Case |
|---|---|---|
| Du Bois (1916) | 0.007184 × W0.425 × H0.725 | Original reference standard; widely cited in research and historical clinical data. |
| Mosteller (1987) | √(W × H ÷ 3600) | Most commonly used in modern clinical practice due to its simplicity and strong agreement with the Du Bois formula. |
| Haycock (1978) | 0.024265 × W0.5378 × H0.3964 | Often preferred for pediatric and neonatal populations; validated across a wider age range including infants. |
Why BSA Alone Is Not a Full Picture
BSA is a powerful clinical tool, but it is not a standalone health assessment. A single BSA value does not reveal whether a person is underweight, overweight, or has a healthy body composition. Two individuals with identical BSA can have very different ratios of muscle to fat, different metabolic rates, and different overall health profiles.
BSA is most useful when applied as part of a broader clinical context — for example, when calculating a chemotherapy dose, the clinician also considers organ function, performance status, and prior treatment response. For general wellness tracking, BSA is less informative than BMI, waist circumference, or body composition measurements.
Known Limitations
- BSA formulas are population-derived estimates, not direct measurements. Actual surface area varies with body shape, posture, and individual anatomy.
- The Du Bois formula was derived from only nine subjects, which limits its statistical generalizability across diverse populations.
- BSA formulas may be less accurate at extremes of height and weight (very tall, very short, underweight, or severely obese individuals).
- BSA does not account for body composition — two people with the same BSA can have very different fat-to-muscle ratios.
- BSA is not a fitness metric. It was designed for medical dosing and physiological normalization, not for tracking weight or health status over time.
Scenario guide
Scenario guide
Disclaimer: This page is for educational purposes only. Chemotherapy dosing is determined by oncologists based on numerous clinical factors. Never self-administer or adjust chemotherapy doses based on any online calculator.
Why BSA is used for chemotherapy dosing
Most chemotherapy drugs are dosed based on body surface area (BSA) rather than body weight alone. This is because BSA correlates better than weight with several pharmacokinetic parameters: cardiac output, renal blood flow, and glomerular filtration rate — all of which influence how drugs are distributed and cleared from the body.
The Mosteller formula for BSA
The Mosteller formula is the most widely used BSA calculation in oncology:
BSA (m²) = √(Height (cm) × Weight (kg) / 3600)
Example: 170 cm, 70 kg → BSA = √(170 × 70 / 3600) = √(3.21) = 1.79 m²
How chemotherapy doses use BSA
Most chemotherapy regimens specify a dose in mg/m² (milligrams per square meter of BSA). For example, if a drug is prescribed at 75 mg/m² and your BSA is 1.8 m², your dose would be 75 × 1.8 = 135 mg.
BSA-based dosing helps standardize drug exposure across patients of different sizes, reducing the risk of underdosing (reduced efficacy) in larger patients and overdosing (excessive toxicity) in smaller patients.
Important clinical considerations
- Actual vs. ideal BSA: Oncologists may use actual body weight or adjusted weight for BSA calculation, depending on the patient\'s nutritional status and the specific drug
- Obesity: In obese patients, using actual body weight BSA can lead to excessive dosing. Many oncologists cap BSA or use adjusted weight
- Cachection: In severely underweight or cachectic patients, ideal BSA may be used to avoid underdosing
- Renal/hepatic function: BSA dosing is adjusted further based on kidney and liver function tests
Limitations of BSA-based dosing
BSA-based dosing is an approximation, not an exact science. It does not account for individual differences in drug metabolism, body composition, or genetic variations in drug-processing enzymes. Therapeutic drug monitoring (when available) and clinical response assessment are the ultimate guides for dose adjustment.
FAQ
Frequently Asked Questions
BSA correlates better with cardiac output, renal blood flow, and glomerular filtration rate — all of which influence how chemotherapy drugs are distributed and cleared. This makes BSA a more accurate dosing parameter than weight alone.
Most chemo drugs are prescribed in mg/m². Multiply the prescribed dose (mg/m²) by your BSA (m²) to get the actual dose. Example: 75 mg/m² × 1.8 m² = 135 mg.
The Mosteller formula is most widely used in oncology: BSA = √(height × weight / 3600). Some institutions use Du Bois or Haycock formulas, but Mosteller is the standard.
Most, but not all. Some newer targeted therapies and immunotherapies use flat dosing (same dose for all patients) rather than BSA-based dosing.
BSA is an approximation. In obese patients, using actual weight BSA can overestimate the dose. In cachectic patients, it can underestimate. Oncologists adjust based on clinical judgment and patient condition.
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