Body surface area (BSA) is the total area of your skin, in square meters. Doctors use it to dose some drugs, chemotherapy among them, and to size measurements such as cardiac output to the person. It comes from height and weight alone, so it says nothing about how much of that weight is fat or muscle.
Example: Male, 5 ft 9 in, 155 lb
1.85square meters: your body surface area, Mosteller formula
By the Mosteller formula your body surface area is 1.85 m² (19.9 sq ft). The eight formulas give 1.77 to 1.87 m² for you.
Doctors use body surface area to dose some drugs, cancer chemotherapy among them, and in burn care. Each formula was fitted on its own group of people, so the eight give slightly different answers. Enter your own numbers above to replace this example.
All eight formulas
1.77 to 1.87 square meters
The highest is 6% above the lowest for your height and weight.
| Formula | Square meters | Square feet |
|---|---|---|
| Mosteller (1987)The square root of height times weight over 3,600 | 1.85 m² | 19.9 sq ft |
| Du Bois (1916)The oldest; reads low under 0.7 m² (Haycock 1978) | 1.85 m² | 20.0 sq ft |
| Haycock (1978)Checked from premature babies to adults | 1.85 m² | 19.9 sq ft |
| Gehan and George (1970) | 1.86 m² | 20.0 sq ft |
| Boyd (1935) | 1.86 m² | 20.0 sq ft |
| Takahira (1925) | 1.87 m² | 20.1 sq ft |
| Fujimoto (1968)From 201 Japanese people; for ages 6 and up | 1.80 m² | 19.4 sq ft |
| Schlich (2010)Separate versions for men and women; this is yours | 1.77 m² | 19.0 sq ft |
- Next stepBMI calculatorWeight for height as a health screen, the other common height and weight number.
- Next stepBody fat calculatorHow much of your weight is fat, which body surface area cannot show.
Formula: Mosteller: BSA = square root of (weight kg x height cm / 3600). Weight in kilograms and height in centimeters; 1 square foot is 0.0929 m².
Sources: Kuehnapfel et al. 2017 (Eur J Appl Physiol); Redlarski et al. 2016 (Sci Rep); Haycock et al. 1978 (J Pediatr); Fujimoto et al. 1968 (Jpn J Hyg)
What is body surface area used for?
Body surface area is used to assess heart function in relation to body size (cardiac output). It’s also used to help find optimal medication dosages as body size plays a role in determining an appropriate dose for effective treatment.
Chemotherapy treatment dosages are often administered using the BSA calculation as well as renal clearance and glucocorticoid dosing. Although, there has been opposing opinion about using this method for chemotherapy especially because certain drugs used for treatment have a narrow therapeutic index. This would cause serious adverse effects. But these methods are used in a clinical and lab setting.
Most Accurate Method For Calculating BSA
Finding the exact BSA of an individual is not always accurate or simple. The first formula was developed by Du Bois in 1916 but since then, there have been many formulas developed that are used to help determine an approximation of BSA.
Although, we do recommend using the Du Bois or Mosteller formula as these are the most widely used formulas. (1)
Du Bois is the oldest; Mosteller gives almost the same answer and is simple enough to remember.
You can, however, experiment with the different formulas to see how they affect your results.
BSA (body surface area) vs. BMI (body mass index)
This method of calculation is often compared to BMI (body mass index) to determine body mass values and markers of health.
However, there are some differences. For instance, BMI is a basic, commonly used tool for determining a healthy body weight range. It does a decent job at this and is used for this purpose in a healthcare setting as well. BMI is calculated based on height and weight. It’s also used to determine an individual’s potential for health risk.
But what BMI doesn’t do, is consider whether someone has a decent amount of muscles (sports athletes, bodybuilders, etc). Consequently, body fat may be overestimated. It also doesn’t consider age or muscle loss. So, one may be less or more healthy, in general, than what the calculator estimates.
The BMI formula takes the body weight in kg and divides it by height in meters squared. Then, it’s measured against predetermined values to determine the health range based on an individual’s body weight. In contrast, a formula such as the Mosteller takes the square root of the height (cm) multiplied by the weight (kg) divided by 3600.
Now, the average adult BSA is 1.7 m2 (1.9 m2 for adult men and 1.6 m2 for adult women). But age and sex also play a role in addition to height and weight.
Compare your result with the typical values for newborns, children and adults in the table below.
Table of BSA averages
| ft2 | m2 | |
| Newborn child: | 2.69 | 0.25 |
| Two-year-old child: | 5.38 | 0.5 |
| Ten-year-old child: | 12.27 | 1.14 |
| Adult female: | 17.22 | 1.6 |
| Adult male: | 20.45 | 1.9 |
Formulas Used In The Calculator
There are several formulas that you can select when computing your BSA which is expressed in the following formulae by weight (W) in kg, and height (H) in cm. There generally isn’t a big difference between these formulas and it’d be impossible to be perfect with your calculations.
Du Bois formula:
BSA = 0.007184 × W0.425 × H0.725
Mosteller formula:
BSA = 0.016667 × W0.5 × H0.5
Haycock formula:
BSA = 0.024265 × W0.5378 × H0.3964
Gehan and George formula:
BSA = 0.0235 × W0.51456 × H0.42246
Boyd formula:
BSA = 0.03330 × W(0.6157 − 0.0188 × log10(W)) × H0.3
Fujimoto formula:
BSA = 0.008883 × W0.444 × H0.663
Takahira formula:
BSA = 0.007241 × W0.425 × H0.725
Schlich formula:
Women BSA = 0.000975482 × W0.46 × H1.08
Men BSA = 0.000579479 × W0.38 × H1.24
What else is body surface area used for?
Outside the clinic, body surface area has few everyday uses. Older metabolic tables gave resting energy per square meter of skin, which is why some BMR methods mention it, but modern energy calculators work from weight, height, age and sex instead. For calories, use the BMR or TDEE calculator; for how much of your weight is fat, use the body fat calculator.
Also try other related calculators:
- Creatine Calculator
- LBM Calculator
- Macronutrient Calculator
- TDEE Calculator
- Carb Cycling Calculator
- Intermittent Fasting Calculator
- Water Fasting Weight Loss Calculator
- Body Fat Calculator
- Weight Loss Percentage
Wrapping Up
The BSA calculator gives your total body surface area in square meters, the number clinics use to scale drug doses and some heart measurements to body size. It says nothing about fat or muscle; for that, use the body fat calculator.
