The Rule of Nines: Burn Assessment to Know for NCLEX

If there’s one burn assessment tool you’re guaranteed to see on the NCLEX it’s the Rule of Nines. This quick-and-easy method helps you estimate how much of a patient’s body surface area (BSA) has been burned. Knowing this calculation will make you feel so much more confident when staring down a burn question (or a real emergency department scenario)!

Let’s break it down in a way that’s easy to remember for the NCLEX.

🔥 Rule of Nines Cheat Sheet!

Looking for a prettier rule of nines chart to help you visualize? Download the FREE Rule of Nines Cheat Sheet from Blueprint Nursing, including a practice question to test your knowledge!

🌟 What is the Rule of Nines?

The Rule of Nines is a quick way to estimate the total body surface area (TBSA) affected by burns in adults. Each major body region is assigned a percentage that adds up to 100%.

Why does that matter? Because the TBSA determines:

How serious the burn is
Which treatments you prioritize
Whether the burn center needs to be involved
Fluid resuscitation calculations like the Parkland formula

So yes, the math actually matters here!

🧠 The Percentages You MUST Memorize

Here’s the breakdown:

Head + Neck: 9%
Each Arm: 9%
- (Both arms together = 18%)
Each Leg: 18%
- (Both legs together = 36%)
Anterior Trunk: 18%
Posterior Trunk: 18%
Genitalia/Perineum: 1%

Add all those up and you get a perfect 100%.

👶 It’s A Bit Different for Young Children…

The standard Rule of Nines works great for adults and older children, but not so much for infants and toddlers. Their proportions are different:

Babies have bigger heads relative to body size
Their legs make up a smaller percentage

So for the NCLEX, remember: there’s a modified version for pediatric patients. The exam might not make you calculate it, but they will expect you to know that adult percentages don’t apply.

✋ The Palmer Method (a Backup Trick You’ll Love)

What about those weird, irregular-shaped burns that don’t match up nicely with trunk/arm/leg percentages?

Hello, Palmer Method.

You use:

👉 The patient’s palm = 1% TBSA

This is perfect for small burns (i.e. contact burns, scalds, or scattered areas) when the Rule of Nines isn’t precise enough.

🧯 Common NCLEX Traps to Watch For

Burn questions love to be sneaky. Keep your guard up for:

Children listed with adult percentages
Partial vs. full anterior/posterior involvement
Only one side of a limb burned
Genital burns (don’t forget that 1%)!
Irregular burns where the palm method is better

Always break the scenario down piece by piece, and keep track of your percentages as you go.

Keep Going!

Looking for a full breakdown of the rule of nines and a practice question? Check out our Rule of Nines lesson on YouTube—Abby walks you through everything step-by-step!