Body Surface Area (BSA) Calculator — Mosteller Formula
Calculate your body surface area using Mosteller, Du Bois, and Haycock formulas. Includes formula comparison panel, BSA reference chart, and mandatory clinical dosing warning.
BSA Calculator
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√(H × W ÷ 3600)
0.007184 × W^0.425 × H^0.725
0.024265 × W^0.5378 × H^0.3964
Mosteller Formula
BSA = √(Height × Weight ÷ 3600)
BSA Reference
1.73
Avg Adult m²
1.0
Child m²
0.5
Infant m²
2.0
Large Adult m²
⚠ Clinical Usage — Educational Purposes Only
This BSA calculation is for educational reference only. All clinical dosing decisions — including chemotherapy, pediatric medications, and other treatments requiring BSA — must be verified by a licensed pharmacist or physician. Different institutions may use different BSA formulas for different protocols. Using an incorrect BSA value for drug dosing can result in underdosing or potentially toxic overdosing. This tool provides estimates and is not a substitute for professional clinical judgment.
The Formula
Body Surface Area estimates the total external surface area of the human body. The Mosteller formula is the most widely used clinically because of its simplicity. BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is used for chemotherapy dosing, burn severity assessment (rule of nines), and certain medication calculations where weight-based dosing is insufficient. The average adult BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is 1.7 m².
Variable Definitions
Body Surface Area
Total surface area of the body in square meters. Used clinically for medication dosing and burn assessment.
Mosteller Formula
BSA = √(Height × Weight ÷ 3600). The most commonly used formula — simple, accurate, and recommended by the FDA for oncology dosing.
Du Bois Formula
BSA = 0.007184 × W^0.425 × H^0.725. The original BSA formula developed in 1916 from direct measurement of 9 subjects.
How to Use This Calculator
- 1
Select your unit system (Imperial or Metric).
- 2
Enter your weight and height.
- 3
Review your BSA from all three formulas — Mosteller is the clinical standard.
- 4
Note the average BSA across all formulas for comparison.
- 5
Read the clinical warning: this is for educational purposes, not medical decision-making.
Common Applications
- Chemotherapy dosing — oncologists use BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. to calculate chemotherapy drug doses, as drug distribution correlates better with surface area than body weight
- Burn severity assessment — the "rule of nines" estimates burn surface area as a percentage of total BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois., guiding fluid resuscitation and treatment decisions
- Clinical medication dosing — certain medications (e.g., immunosuppressants, some anesthetics) use BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois.-based dosing where weight-based dosing is insufficient
- Cardiac output indexing — cardiac index (cardiac output divided by BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois.) normalizes heart function measurements across patients of different sizes
BSA estimates total body surface area using height and weight; the Mosteller formula is the clinical standard
Understanding the Concept
Body Surface Area (BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois.) is a clinical measurement used primarily for chemotherapy dosing, determining burn severity, and adjusting certain medication doses that cannot be based on weight alone. BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is preferred over weight for chemotherapy because drug distribution correlates better with surface area than mass. The Mosteller formula (√(H×W/3600)) is the most widely used because it requires only a simple calculator. The average adult BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is approximately 1.7 m². BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. increases with both height and weight but not linearly — two people of the same weight but different heights will have different BSAs. For example, a tall thin person and a short heavy person might have the same weight but very different BSAs due to the height factor. BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is also used in the 'rule of nines' for assessing burn surface area, in cardiac output indexing (cardiac index = cardiac output / BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois.), and in renal function assessment (eGFRA blood test-based estimate of kidney function. Lower values may indicate chronic kidney disease. is normalized to 1.73 m²). The Du Bois formula was developed in 1916 from direct measurements of only 9 subjects — remarkably, it has proven quite accurate despite the tiny sample. The Haycock formula is preferred for infants and children because it was validated on a population that included pediatric subjects. BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois. is also relevant in sports physiology: the 'body surface area rule' influences heat dissipation capacity, which is why smaller athletes (lower BSAA measurement used in medical dosing, calculated from height and weight. Common formulas include Mosteller and Du Bois.-to-mass ratio) may be more prone to heat stress in endurance events.
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