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BSA Calculator – Body Surface Area

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The BSA formulaWhy use this body surface area calculator?How to calculate BSAOther considerationsFAQs

The BSA calculator allows you to easily find your body surface area (BSA), which is the external surface area of the human body given in square meters. If you know how to calculate BSA, you will find it very useful in medicine and physiology, as some say it may be a more accurate indicator of metabolism than body weight. This is why many doctors base their prescriptions on the BSA formula.

However, you may simply find it interesting to calculate your body surface area. Scientists have established that the whole human circulatory system is over twice as long as the circumference of the Earth if you were to stretch it out. If you know how to calculate BSA, you can find out how many square meters the surface of your body would cover if it could be unraveled and laid out. We hope you find this more interesting than morbid.

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;
  • How to calculate BSA;
  • Other calculators you should check out if you are interested in this topic.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. All information on this website is for informational purposes only and is not intended to serve as a substitute for medical consultation. Always consult your results with a health care provider.

The BSA formula

Many different formulas can be used to calculate body surface area. Our BSA calculator uses the most common form, the Du Bois formula, by default.

There are, however, many different BSA formulas in the Additional BSA calculations section (Fujimoto, Gehan & George, Haycock, and Mosteller).

All you need to use any of these formulas is your weight and height. Let's take a look at a few of them.

Here are the formulas:

Du Bois:

BSA=0.007184×weight0.425×height0.725\scriptsize \text{BSA} \!= \!0.007184 \times \!\text{weight}^{0.425} \!\times \text{height}^{0.725}

Mosteller:

BSA [m2]=height [cm]×weight [kg]3600\scriptsize \text{BSA [m}^2] \!= \!\sqrt{\frac{\text{height [cm]} \times\text{weight [kg]}}{3600}}

Haycock:

BSA=0.024265×weight0.5378×height0.3964\scriptsize \text{BSA} \!= \!0.024265 \times \!\text{weight}^{0.5378} \!\times \text{height}^{0.3964}

Gehan and George:

BSA=0.0235×weight0.51456×height0.42246\scriptsize \text{BSA} \!= \!0.0235 \times \!\text{weight}^{0.51456} \times \text{height}^{0.42246}

Fujimoto:

BSA=0.008883×weight0.444×height0.663\scriptsize \text{BSA} \!= \!0.008883\! \times \!\text{weight}^{0.444} \times \text{height}^{0.663}

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.

Let's try one calculation using the Mosteller formula:

  1. Take your height in centimeters, e.g., 170.
  2. Take your weight in kilograms, e.g., 60.
  3. Multiply your height by your weight, 170 × 60 = 10200.
  4. Divide the result by 3600, 10200/ 3600 = 2.8.
  5. Find the square root of the result, SQRT 2.8 = 1.67.

If you are 170 cm tall and weigh 60 kg, the approximate calculation of your body surface area is 1.67 meters squared.

Some medical practitioners prefer other BSA formulas, such as Haycock or Gehan & George.

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 tedious calculations by using the body surface area calculator. Thanks to this tool, you can find your body size as if it were a flat area. Although 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.

How to calculate BSA

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 plugging in these two values, you automatically get a result.

Let's check our previous example:

  1. Weight (kg): 60
  2. Height (cm): 170

With these measurements, your body surface area equals about 1.69 square meters.

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 body surface area for:

  • Infants: 0.25 m²
  • Children of 2 years: 0.5 m²
  • Children of 10 years: 1.14 m²
  • Women: 1.6 m²
  • Men: 1.9m²

Other considerations

If you are interested in different measurements related to your body, you should also check our BMI calculator. Another calculator you might find useful is our water intake calculator.

It is worth noting that although BSA is a good indicator of metabolic rate, it has received some critique. The most important of which is to use it to determine the dosage of medications that don't have much margin for error, such as chemotherapy.

FAQs

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

The BSA – body surface area – equals 1.8 m2.

To calculate it:

  1. Convert the weight to kg by dividing them by 2.2046.

    163/2.2046 = 73.94 kg

  2. Convert the height to inches and then to cm (multiplying by 2.54).

    5 ft 4 in = 64 in
    64 × 2.54 = 162.56 cm

  3. Use, for example, the Du Bois formula.

    BSA = 0.007184 × weight0.425 × height0.725

  4. Plugging in the values:

    BSA = 0.007184 × 73.940.425 × 162.560.725 = 1.7932 m2

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:

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

What does a BSA of 1.73 mean?

A BSA of 1.73 means the body surface area is equal to 1.73 m2 (approx. 18.62 ft2).

This value is often mentioned as a reference value, as it is the estimated body surface area of a 70 kg (thus – 'average adult') human. It is also used in the estimations of GFR – glomerular filtration rate.

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.

  1. Measure your weight in lbs.
  2. Get your height in inches.
  3. Multiply the weight and height.
  4. Here comes the change – you have to divide the result by 3.131 (in the 'normal' formula, we divide by 3600).
  5. Proceed as usual – find the square root of the last result, and that's it.
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