Body Surface Area Calculator

BSA Calculator

What is BSA?

Body surface area (BSA) is the method that is mostly used in medicine and physiology. BSA medical is the computed or calculated surface area of a human body.

BSA is one sign that is used mostly for medical purposes to determine the total metabolic mass as compared to body weight and the advantage using BSA is that it is less affected by the abnormal adipose mass.

The values of BSA are used mostly in medicine, mainly used to calculate index cardiac output and doses of chemotherapeutic agents.

Here are some examples:

  • Renal clearance often divided by the BSA that is per 1.73 m² to gain a rise in the true GFR (glomerular filtration rate)
  • Glucocorticoid medication are given according to BSA to measure maintenance of medicine doses or used to compare high medicine usage with the maintenance conditions
  • Chemotherapy dosage is sometimes given according to the value of BSA of the person
  • The cardiac index is the calculation of cardiac output which is then divided by the BSA, giving a better estimate of the in effect cardiac output.

The average value of BSA

Average BSA changes according to age, height, and weight in a person. The average value in an adult is 1.7 m2.

Average value in adult male= 19.2 m2

The average value in an adult female is =16.2 m2 

Here is a table for BSA according to age and average values:

Mean male BSA by age
Age or age group metric imperial
Neonate (newborn) 0.243 m2 2.612 ft2
2 years 0.563 m2 6.060 ft2
5 years 0.787 m2 6.060 ft2
10 years 1.236 m2 13.304 ft2
13 years 1.603 m2 17.255 ft2
18 years 1.980 m2 21.313 ft2
20-79 years 2.060 m2 22.173 ft2
80+ years 1.920 m2 20.667 ft2
Mean female BSA by age
Age or age group metric imperial
Neonate (newborn) 0.234 m2 2.519 ft2
2 years 0.540 m2 5.813 ft2
5 years 0.771 m2 8.299 ft2
10 years 1.245 m2 13.401 ft2
13 years 1.550 m2 16.684 ft2
18 years 1.726 m2 18.579 ft2
20-79 years 1.830 m2 19.697 ft2
80+ years 1.638 m2 17.631 ft2


The table shows the estimations which are based on height and weight. These are the mean values commonly found in people and might change as per the situation.

How to Calculate BSA?

BSA calculations involve various formulas that are used to calculate BSA (m2) by using Weight (kg), height (cm).

Here is a body surface area chart estimating average BSA of adults and children:

  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

You can calculate BSA manually or you can use our Body surface area calculator to speed up the process of calculation with precision the most abundantly used formula to calculate is Du Bois, Du Bois BSA equation which is quite effective while calculating body fat in obese and underweight persons as compared to Body mass index.

Du Bois Formula: {BSA} =0.007184×W0.425× H0.725

This formula is simple and easy to remember.  

Other BSA formulas in m2 include:


Gehan and George: 0.0235 × W0.51456 × H0.42246

Fujimoto: 0.008883 × W0.444 × H0.663

Takahira: 0.007241 × W0.425 × H0.725

Schlich:  0.000975482× W0.46 × H1.08 (for men)

                  0.000579479 × W0.38 × H1.24 (for women)

These are some of the other body surface area formulas that can be used to manually calculate a person’s BSA. These formulas look similar to BMI but there is a significant difference between two which is discussed below.

The other way to find BSA is to use our body surface area calculator.

Online BSA calculator

However, there are multiple formulas that are used to calculate BSA but the easiest and human error-free is to use online tools. Our developers have made this online tool to help people quickly get results rather than putting values in the formula to get desired results.

Our tool is quick and user-friendly, all you need to know is your weight and height and insert them in the provided area in any unit like for height inches, cm, feet, and meters.

After putting the values just click on the Calculate button to get results. You can use the results for further examination by your doctor to check the risks and suggest your medication according to it.

BMI and BSA: Are they different?

People often get confused between both terms although they are quite similar as they both are used to determine Body mass.

Body Surface area and Body mass index are different to some extent that one is used to measure the surface area of a person’s body and the other is used to calculate the degree of obesity in a person.

Furthermore, the formulas are also different:

The SI unit for BSA is m2 and unit for BMI is kg/m2. These are different terms and should not be confused. Both BSA and BMI are clinically used in different areas and according to the situation.

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