Body Surface Area Calculator

1. Choose your unit system. Select Imperial (pounds and feet/inches) or Metric (kilograms and centimeters).
2. Enter your weight. Use your current body weight. For drug dosing purposes, some protocols use ideal body weight or lean body weight instead of actual weight. Follow your physician's guidance on which to use.
3. Enter your height. Measure without shoes, standing as straight as possible.
4. Compare the four formula results. The Mosteller formula is used most commonly in clinical practice. DuBois is the historical standard. Haycock is preferred for children. Gehan-George is common in oncology.

Several validated formulas exist for estimating body surface area. All use height in centimeters and weight in kilograms:

Mosteller (1987):
BSA = sqrt(height_cm × weight_kg / 3600)

DuBois & DuBois (1916):
BSA = 0.007184 × height_cm^0.725 × weight_kg^0.425

Haycock (1978):
BSA = 0.024265 × height_cm^0.3964 × weight_kg^0.5378

Gehan & George (1970):
BSA = 0.0235 × height_cm^0.42246 × weight_kg^0.51456

Worked example (Mosteller): Person is 178 cm tall and weighs 80 kg:

BSA = sqrt(178 × 80 / 3600)
    = sqrt(14240 / 3600)
    = sqrt(3.956)
    = 1.989 m²

The average adult BSA is approximately 1.7 m² (range 1.4 to 2.2 m² for most adults). The Mosteller formula became popular because it is simple to calculate without logarithms and produces results within 1-2% of more complex formulas for most body types.