Body Surface Area Calculator

Mosteller for adults, unless something tells you otherwise. It is the simplest — the square root of height in centimetres times weight in kilograms, divided by 3600 — and it sits close to the middle of the five for ordinary adult bodies, so nothing is lost by the simplification. Paediatric protocols often specify Haycock, which was fitted across neonates to adults. What matters far more than the choice is that everyone treating the same patient uses the same one.

They are separate regressions fitted to different people. Du Bois and Du Bois had nine subjects in 1916; Gehan and George refitted the same algebraic shape against 401 direct measurements in 1970; Haycock used 81 subjects spanning newborns to adults in 1978. Each is a best fit to its own sample, so away from the middle of that sample they drift apart. For a typical adult the five land within about one percent of each other, but for a small child the gap widens to several percent.

Roughly 1.9 m² for an average adult man and 1.6 m² for an average adult woman. A ten-year-old is near 1.1 m², and a term newborn of about 50 cm and 3.5 kg lands between 0.21 and 0.23 m² depending on which of the five you read — pick an infant option above and you can check that here. The round 0.25 m² often quoted for a newborn sits a little above every formula on this page. The figure 1.73 m² appears constantly in clinical work because it was taken as the average adult surface area, and kidney function is still reported normalised to it as mL/min/1.73m².

No. BSA-based dosing is a clinical decision that starts from measured, verified height and weight and then applies protocol rules this page knows nothing about — dose capping at 2.0 or 2.2 m², rounding to a vial size, adjustment for organ function, and which formula that particular protocol mandates. Treat the number here as a reference calculation only, and never as a check on a prescribed dose.

Because several things that determine what a drug does — resting metabolic rate, blood volume, glomerular filtration — scale closer to surface area than to mass. A person twice the weight of another does not have twice the clearance. BSA dosing is an imperfect proxy and has been criticised for exactly that reason, but it remains the convention in oncology.

Enter the height in inches after picking one of the "in, lb" options — 5 ft 10 in is 70 inches. Changing that selector converts what you have already typed rather than reinterpreting it, so the body you described stays the same body. All five formulas are defined in centimetres and kilograms, so imperial input is converted before any of them run.

Yes — choose one of the infant options and enter the recumbent length rather than a standing height. It is a separate choice rather than simply a lower limit on the same box because a newborn measures about 50 cm, and 50 to 78 is also the range someone types when they mean inches but leave centimetres selected. Without knowing which you meant, the page would have to either refuse real babies or answer a mistyped adult as one. Read the Haycock figure for an infant: it was fitted from neonates upward, while Du Bois came from nine adults and drifts furthest at this size.