# Body surface area

In physiology and medicine, the body surface area (BSA) is the measured or calculated surface of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume.

## Uses

Examples of uses of the BSA:

## Calculation

Various calculations have been published to arrive at the BSA without direct measurement, starting in 1916 with the Dubois & Dubois formula. A commonly used formula is the Mosteller formula, published in 1987:

Metric (area in square metres from weight in kilograms and height in centimetres):

${\displaystyle {x}={\sqrt {\frac {{\mbox{weight}}\times {\mbox{height}}}{3600}}}}$

half-English units (area in square metres from weight in pounds, height in inches):

${\displaystyle {x}={\sqrt {\frac {{\mbox{weight}}\times {\mbox{height}}}{3125}}}}$

Another is the Haycock formula (in children):

${\displaystyle {x}=0.024265\times {weight{\mbox{ (kg)}}}^{0.5378}\times {height{\mbox{ (cm)}}}^{0.3964}}$,

Du Bois & Du Bois, Arch Intern Med 1916;17:863:

${\displaystyle {x}=(71.84\times {weight{\mbox{ (kg)}}}^{0.425}\times {height{\mbox{ (cm)}}}^{0.725})/10000}$,

Gehan EA, George SL, Cancer Chemother Rep 1970;54:225-235:

${\displaystyle \mathrm {S} =0.0235\times height{\mbox{ (cm)}}^{0.42246}\times weight{\mbox{ (kg)}}^{0.51456}}$ ,

Boyd's Formula:

${\displaystyle \mathrm {S} =0.0003207\times height{\mbox{ (cm)}}^{0.3}\times weight{\mbox{ (g)}}^{(0.7285-0.0188\log _{10}{weight\mathrm {(g)} })}}$.

## Normal values

• "Normal" BSA is generally taken to be 1.7 m².
• Average BSA for men: 1.9 m²
• Average BSA for women: 1.6 m²
• Average BSA for child (9 years): 1.07 m²
• Average BSA for child (10 years): 1.14 m²
• Average BSA for child (12-13 years): 1.33 m²
• Average BSA for neonate: 0.25 m2
• Average BSA for 2 year old child: 0.5 m2

## References

• Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098. PMID 3657876.
• 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;93:62-66