Body Surface Area (BSA) Calculator
Calculate body surface area using Mosteller, DuBois, Haycock, and Gehan-George formulas for drug dosing and clinical assessments.
About this calculator
Body surface area estimates the total area of skin covering the body from just two measurements, height and weight, and every formula here folds both into a single number that rises whenever either input rises -- there is no configuration of Height and Weight where increasing one lowers the result. Mosteller's formula, BSA = sqrt(height x weight / 3600), was published by Richard Mosteller in the New England Journal of Medicine in 1987 and is the one most clinical references default to because it is simple to compute by hand and validated across the widest range of body sizes, from a 52 cm neonate (about 1.01 m2) to a tall, heavy adult approaching 2.1 m2. DuBois (1916), Haycock (1978), and Gehan-George (1970) each fit the same two inputs with different power-law exponents derived from their own measured cohorts, so they agree closely with Mosteller near an average adult build and diverge more at the extremes of height and weight -- which is exactly why the calculator shows all four side by side rather than picking one.
BSA itself is not a diagnosis; it is a normalizing factor. Chemotherapy doses are commonly prescribed in mg per m2 specifically so a drug's exposure scales with a patient's body size rather than weight alone, and BSA is used the same way for burn-surface estimates and for indexing cardiac output to a patient's size. An average adult BSA is roughly 1.7 m2, but the four formulas on this page will not agree to the decimal -- expect small, formula-dependent differences rather than one authoritative figure.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Average adult BSA: female ~1.6 m²; male ~1.9 m²; chemotherapy dosing per BSA m²; neonates ~0.2 m²
Results
Mosteller BSA
1.82m²
≈ 29 sheets of paper
Figures current as of 1987. Sources: Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098., Du Bois D, Du Bois EF. Clinical calorimetry: tenth paper. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;17(6_2):863-871., 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.
How to Use This Calculator
- Enter patient height in cm and weight in kg.
- Review BSA by Mosteller, DuBois, Haycock, and Gehan-George formulas (m²).
- Use the Mosteller formula for most dosing contexts — it is the most widely validated.
How the result changes with Height
| Height | Mosteller BSA |
|---|---|
| 85 | 1.29m² |
| 128 | 1.58m² |
| 250 | 2.21m² |
What each input means
- Height
- Patient height in centimeters.
- Weight
- Patient weight in kilograms. BSA is used for chemotherapy dosing (mg/m²), burn assessment, and cardiac output indexing. Average adult BSA: ~1.7 m² (Mosteller formula: BSA = √(H×W/3600)).
How this is calculated
Worked example, using the default values
- Identify Input ParametersHeight = 170, Weight = 70 = 2 input(s) provided
- Calculate Mosteller BSAMosteller BSA1.818 = 1.818
- Calculate DuBois BSADuBois BSA1.81 = 1.81
- Calculate Haycock BSAHaycock BSA1.826 = 1.826
Figures and sources
- Mosteller formula for body surface area (1987) — Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098.
- DuBois formula for body surface area (1916) — Du Bois D, Du Bois EF. Clinical calorimetry: tenth paper. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;17(6_2):863-871.
- Haycock formula for body surface area (pediatric-validated) (1978) — 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.
Engine last updated . Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why do the four BSA formulas give slightly different numbers for the same height and weight?
Each formula is a power-law fit -- a constant multiplied by height and weight raised to their own exponents -- calibrated against a different measured cohort (DuBois 1916, Gehan-George 1970, Haycock 1978, and the simpler Mosteller square-root formula). They agree closely for an average adult build and spread apart more at unusual heights or weights, since no single historical cohort covered every body size equally well.
Which BSA formula should I use for drug dosing?
Mosteller is the formula most clinical dosing references default to, since it is simple to compute and has been validated across a wide range of body sizes. The prescribing reference or protocol tied to a specific medication should still be the final word -- some chemotherapy regimens were originally validated against DuBois BSA, and switching formulas can shift the calculated dose by a few percent.
Does raising either Height or Weight ever lower the calculated BSA?
No. Every formula on this page combines Height and Weight with positive exponents, so BSA increases whenever either input increases and the other is held fixed, across this calculator's full 30-250 cm and 1-300 kg ranges. There is no combination where a taller or heavier patient produces a smaller BSA.
Why does BSA matter for chemotherapy dosing instead of just using body weight?
Many drugs' clearance and toxicity scale more closely with metabolic rate and organ size than with raw body mass, and BSA (in m2) tracks those better than weight (in kg) alone across the wide range of adult and pediatric body sizes chemotherapy is prescribed for. Dosing in mg per m2 keeps drug exposure more consistent from a small adult to a large one than dosing in mg per kg would.
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