Rule of Nines for Burns: Adult and Child Values

Burn questions on the NREMT EMT exam usually come in two flavors. One asks you to estimate how much of the body is burned. The other gives you a burn scenario and asks what to do first. The Rule of Nines is the tool for the first kind, and knowing its numbers also helps with the second, because burn size is one of the findings that changes the answer.

This guide gives the adult and pediatric values, the rules about what counts, worked examples, and the surrounding exam content. The numbers come from the burn chapter in Encodr's free NREMT EMT course, which is based on the NASEMSO national model. It is a study aid for the exam. Your EMT program, state protocols and medical director decide how you assess and treat burns in practice.

What the Rule of Nines estimates

The Rule of Nines is a quick estimate of total body surface area (TBSA) burned, expressed as a percent. It splits the body into regions that are roughly 9% or a multiple of 9%, so you can add them up at the scene without a chart.

Two rules decide what you add:

• Only second- and third-degree burns count. Second-degree is partial thickness and third-degree is full thickness. First-degree (superficial, redness only) burns are left out of the TBSA estimate.
• You count the area burned, region by region. A region that is fully burned counts its full value. The values split into front and back halves where that helps.

The adult values

Add them: 9 + 18 + 18 + 9 + 9 + 18 + 18 + 1 = 100.

The pediatric values

A child has a proportionally larger head and smaller legs than an adult, so the head and legs change while the rest stays the same.

That also adds to 100: 18 + 18 + 18 + 9 + 9 + 13.5 + 13.5 + 1. The two changes to remember are head 18 and legs 13.5 each. The course also notes that for children the palm of the patient's hand, not including the fingers, is about 1% of TBSA, which is useful for small or scattered burns.

Worked examples

Adult scald. An adult has blisters across the entire front of the torso and the front of the left arm. Front torso is 18 and the front of one arm is 4.5, so TBSA is 18 + 4.5 = 22.5%. The usual slip is forgetting that one arm's front is only 4.5, not 9.

Child with a head burn. A child has burns over the entire head. The pediatric head is 18%, not 9%, so the estimate is 18%.

Leg burn. A whole adult leg, front and back, is 9 + 9 = 18%. A whole child's leg is 6.75 + 6.75 = 13.5%.

Mixed. An adult has second-degree burns to the back of the torso (18), the front of the right leg (9) and the head front and back (9). That is 18 + 9 + 9 = 36%.

You can tick regions and see the sum, for adults and children, in the Rule of Nines calculator. Use it to check your own addition, and do the sums by hand first.

Where burn size shows up in the rest of the exam

TBSA is not the whole answer. The burn chapter ties it to several other decisions:

• Burn center transport. The national model suggests considering direct transport to a burn center for partial- or full-thickness burns above 10% TBSA, and for burns of the hands, feet, genitalia or face, or circumferential burns. A small partial-thickness burn on a thigh does not meet that bar, but a partial-thickness burn involving the hands or face does.
• Airway first. A patient rescued from a house fire with a hoarse voice and soot at the nares has a probable airway burn, even if SpO2 reads 99%. Stridor or a change in voice are sentinel signs that can progress to obstruction, and pulse oximetry can be misleading with carbon monoxide. High-flow oxygen and rapid transport are the exam answer.
• Treat the burn simply. Stop the burning, remove jewelry and wet or non-stuck clothing, cover with a dry dressing or clean sheet, keep the patient warm, and apply no gels or ointments.
• Shock is a clue. A burned patient in shock within about an hour of the injury is probably not in shock from the burn itself, so look for associated trauma.
• Chemical burns. A dry powder chemical is brushed off before the skin is flushed with water.

These pieces sit across the trauma and assessment chapters, so they reward a connected view. EMT patient assessment, step by step shows where a burn fits in the primary survey, and how to study for the NREMT EMT exam places the burn chapter in the wider plan.

How to memorize it

The adult table has only a few numbers, and they are all multiples of 4.5, so the work is practicing the sums, not rote recall. Quiz yourself with a region list, say the value out loud, then add. For the pediatric version, drill only the two differences. Testing yourself beats rereading the table, and spacing the practice over several days holds the numbers better than one long session, which the research on spacing supports.

If you also use the GCS calculator for the assessment chapters, you have both of the number-crunching tools for the assessment and burn chapters.