Calculating Amount of Burn


This is how doctors calculate how much of your body area has been burned by a dry or wet substance.

It’s important because it will allow your doctor to figure out how much fluids to replace, an important consideration as they figure out what kind of care to provide as they transfer you to a burn center that handles this kind of patient.


This is the world of the trauma specialist. They know what they’re doing. This is only for general education purposes.


Here’s the general equation for calculating the percentage of body that has been burned.

Rule of 9s: 18 on back, 18 on front, 9 head, 9 arm, 9 leg; 18 child head

Once the percentage of body burned is calculated, another formula allows the clinician to calculate how much fluids will need to be replaced.

4 x SA x kg = ml NS, First 1/2 in 8H

Four times the surface area calculated by the rule of nines above

times the patient’s weight in kilograms…

Will yield the amount of cc of normal saline that needs to be replaced by IV.

The first half of that must be replaced in eight hours.


There’s other ways of calculating this.

This is the most commonly used method.