Body Surface Area (BSA) Calculator

Body Surface Area Calculator

Quickly calculate your Body Surface Area via BSA calculator online for free!

This Body Surface Area Calculator is based on Mosteller Method.

The BSA calculator allows you to easily calculate your body surface area (BSA), which is the external surface area of the our body given in square meters. If you know how to calculate BSA, you will find it very useful in medicine and physiology, as it is a more accurate indicator of metabolic mass (the body’s need for energy).

However, you may simply find it interesting to calculate your body surface area.

Keep reading if you would like to find out:

What the BSA formula is, and how it can be used to calculate body area;
What is the body surface area calculator;
What are the applications of BSA?
How to calculate BSA manually?
How to calculate BSA;
Other calculators you should check out if you are interested in this topic.

Table of Content

How to Calculate BSA?

With this BSA Calculator, no need to worry about imperial or metric BSA formula.

The easiest way to calculate your body surface area is to use our BSA calculator. This tool needs only your weight and height to solve the equation. After adding in these two values, you automatically get a result.

Let’s check steps:

Enter your height in any unit (inches, meters or centimetres)
Enter your weight and select unit kgs or lbs.
Click on “Calculate” button and your BSA (Body Surface Area) will appear below in square meter.

If you are going to calculate your BSA, it’s good to know the average BSA values. They are divided into categories of age and gender.

The Average BSA Values

Average BSA for different age group is;

Men: 1.9 m²
Women: 1.6 m²
Child (9 years): 1.07 m²
Child (10 years): 1.14 m²
Child (12-13 years): 1.33 m²
Neonate: 0.25 m²
2 year old child: 0.5 m²

General Tips

Check that your answer makes sense clinically.
Triple check your work.
Have a colleague or pharmacist check your work.
Know general therapeutic drug doses for commonly administered medications.

Why use this body surface area calculator?

Luckily for you, there’s no need to calculate your BSA on your own. You can avoid any calculations by using the body surface area calculator. Thanks to this tool, the calculator is based on some complicated equations, it is simple to use and only takes a few seconds if you already know your height and weight.

What are the main BSA formulas?

There are a number of formulas for calculating the BSA, as already stated. We will look into each one of them in detail here. The most widely used of these is the Du Bois formula, which has been shown to be effective for estimating body fat in both obese and non-obese patients, unlike body mass index.

All you need to use any of these formulas is your weight and height.

Here are the formulas:

Du Bois formula:

It is the product of the weight of the person raised to the power 0.425, height raised to the power 0.725 and 0.007184, i.e:

BSA = 0.007184 × W^0.425 × H^0.725

Du Bois D, Du Bois EF (Jun 1916). “A formula to estimate the approximate surface area if height and weight be known”. Archives of Internal Medicine 17 (6): 863-71. PMID 2520314. Retrieved 2012-09-09.

Mosteller Formula:

BSA Mosteller Formula is calculated by multiplying the person’s height in cm with his/her weight in kilograms and dividing the value by 3600. Then take the square root of the resulting value to get the BSA as stated below:

Matric BSA Formula:

Standard BSA Formula:

Mosteller RD. “Simplified calculation of body-surface area”. N Engl J Med 1987; 317:1098. PMID 3657876.

Haycock formula:

It is the product of the weight of the person raised to the power 0.5378, height raised to the power 0.3964 and 0.024265, i.e:

BSA = 0.024265 × W^0.5378 × H^0.3964

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.

Gehan and George formula:

It is the product of the weight of the person raised to the power 0.51456, height raised to the power 0.42246 and 0.0235, i.e:

BSA = 0.0235 × W^0.51456 × H^0.42246

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

Boyd formula:

It is calculated as follows:

BSA = 0.03330 × W^{(0.6157 – 0.0188 × log10(W)} × H^0.3

Boyd, Edith (1935). The Growth of the Surface Area of the Human Body. University of Minnesota. The Institute of Child Welfare, Monograph Series, No. x. London: Oxford University Press

Fujimoto formula:

It is the product of the weight of the person raised to the power 0.444, height raised to the power 0.663 and 0.008883, i.e:

BSA = 0.008883 × W^0.444 × H^0.663

Fujimoto S, Watanabe T, Sakamoto A, Yukawa K, Morimoto K. Studies on the physical surface area of Japanese. 18. Calculation formulae in three stages over all ages. Nippon Eiseigaku Zasshi 1968;5:443-50.

Takahira formula:

Calculation:

BSA = 0.007241 × W^0.425 × H^0.725

Schlich formula:

Here, the BSA for men and women use alternative equations:

For Women BSA:

BSA = 0.000975482 × W^0.46 × H^1.08

For Men BSA:

BSA = 0.000579479 × W^0.38 × H^1.24

Schlich E, Schumm M, Schlich M: “3-D-Body-Scan als anthropometrisches Verfahren zur Bestimmung der spezifischen Korperoberflache”. Ernahrungs Umschau 2010;57:178-183

where BSA is measured in square meters, weight in kilograms, and height in centimeters. Our tool lets you easily use other units, so don’t worry.

Body Surface Area Calculation Steps

Measure the body weight (in kilograms – kg).
Check the height or length (in centimeters – cm).
Use any BSA formula, for example, the Du Bois formula.
Place in the values and calculate:
And you’re done! You can always double-check with our BSA calculator.

BSA Calculation Examples

How do I calculate BSA with a weight of 163 lb and height of 5 ft 4 in?

To calculate it:

Convert the weight to kg (1kg = 2.2046lbs) by dividing them by 2.2046.
- 163/2.2046 = 73.94 kg
Convert the height to inches and then to cm (multiplying by 2.54). 1ft = 12inches and 1inche = 2.54cm.
- 5 ft 4 in = 64 in
- 64 × 2.54 = 162.56 cm
Use, for example, the Du Bois formula.
- BSA = 0.007184 × weight^0.425 × height^0.725
Adding the values:
- BSA = 0.007184 × 73.94^0.425 × 162.56^0.725 = 1.7932 m²

The BSA – body surface area – equals 1.8 m².

You can check dosage calculation conversions here

Applications of BSA

BSA is helpful for calculating the following parameters:

1. Cardiac index(CI):

Cardiac index is calculated by dividing the cardiac output by BSA. The normal range of the cardiac index is 2.5 – 4.0 L/min/m².

2. Stroke volume index(SVI):

Stroke volume index (SVI = stroke volume divided by BSA)

3. Systemic vascular resistance index (SVRI):

Systemic vascular resistance index (SVRI = systemic vascular resistance divided by BSA)

4. Pulmonary vascular resistance index(PVRI):

Pulmonary vascular resistance index (PVRI = pulmonary vascular resistance divided by BSA).

BSA is also used to determine the dosage of medications, to estimate renal clearance, in chemotherapy dosage and glucocorticoid dosage. Several antivirals, antimicrobials, and antifungals require a dosing regimen based on the BSA.

Body Surface Area Limitations

There exist arguments against the use of BSA to determine medication dosages that have a narrow therapeutic index. If the therapeutic index is too narrow, BSA may not be an accurate enough measure, and there is a risk of causing a toxic rather than therapeutic effect.

There is also evidence that BSA becomes less accurate at the extremes of height and weight, and BMI may be a better estimate in such cases.

FAQs

What is BSA?

Body Surface Area (BSA) is simply a measurement of the surface area of your body based on body weight and height.

What is BSA stand for in medical?

BSA stand for Body Surface Area.

How do I calculate BSA for pediatrics?

To calculate BSA for pediatrics (children), you can use the same formulas as usual. For example, a popular option is Mosteller’s formula. To use it:

Measure the child’s weight (in kilograms – kg).
Check the child’s height or length (in centimeters – cm).
Multiply the weight and height.
Divide the result by 3600.
Find the square root of that number.
And you’re done! You can always double-check with our BSA calculator.

How do I calculate body surface area with inches and pounds?

You can use a modified Mosteller’s formula to calculate body surface area (BSA) with inches and pounds.

Measure your weight in lbs.
Get your height in inches.
Multiply the weight and height.
Here comes the change – you have to divide the result by 3,131 (in the ‘normal’ formula, we divide by 3600).
Proceed as usual – find the square root of the last result, and that’s it.

How to calculate BSA nursing?

To calculate Body Surface Area follow these steps

Measure the body weight (in kilograms – kg).
Check the height or length (in centimeters – cm).
Use any BSA formula, for example, the Du Bois formula.
Place in the values and calculate:
And you’re done! You can always double-check with our BSA calculator.

How to calculate childs drug dose based on BSA?

To calculate childs dose based on Body Surface Area we will use Catzel Rule which is utilized to determine the correct pediatric medication dosage based specifically on the patient’s size. The patient’s size is identified as body surface area (BSA) in meters squared (M²). The average adult client (weighing 150 – 154 lbs) will have a BSA of 1.73M².

Learn, how to use Catzel Rule to calculate pediatric drug dose based on BSA?