§ 15

Burn size (9 rule and palm)

How large is the burn as a percentage of the body?

Answer: When you call 112 about a burn, it helps to be able to say how big it is. The 9 rule divides the body into parts of approx. 9 %: head and neck 9 %, each arm 9 %, front of body 18 %, back 18 % and each leg 18 %. In small children the head is larger (18 %) and legs smaller (13.5 % each). Small, scattered burns you measure with the injured person's own hand with fingers, which is approx. 1 %. Specify what fraction of each body part is burned, plus number of hands for spots, so the calculator adds up. It doesn't assess how serious the burn is.

Formula

Adult: head and neck 9 %, both arms 18 %, front 18 %, back 18 %, both legs 36 %, genitals 1 %.

Small child: head and neck 18%, both legs 27% (13.5% each); rest as adults.

Forbrændt % = Σ (kropsdelens procent · den forbrændte del af den) + antal håndflader · 1 %.

The palm of the hand with fingers belongs to the injured person, not you.

Symbols and units in the formula
Symbol	Meaning	Unit
alder	The injured person	—
hoved	Head and neck: part that is burnt	%
arme	Both arms combined: share that is burnt	%
forside	Body front (chest and abdomen): part that is burnt	%
bagside	Body back (back and buttocks): part that is burnt	%
ben	Both legs combined: share that is burnt	%
haandflader	Small patches otherwise: number of palm prints	håndflader
=	Burnt skin in total	%
=	Heraf sma pletter (handfladereglen)	%
=	Of which from body parts (rule of nines)	%

Validity and source

Source: Wallace' 9-regel (voksen og barn) + håndfladereglen: håndflade med fingre ≈ 1 % af huden

Does not apply when

The figure is an estimate for the message to 112 and doctor. It says nothing about depth. Cool the burn and ring 112 as you learned on the course. If in doubt always ring. Redness alone (as with sunscald) usually does not count.

Worked example

The calculator's own default values inserted. The figures are calculated with exactly the formula the tool uses.

Substituted

The injured person1
Head and neck: part that is burnt0 %
Both arms combined: share that is burnt25 %
Body front (chest and abdomen): part that is burnt0 %
Body back (back and buttocks): part that is burnt0 %
Both legs combined: share that is burnt0 %
Small patches otherwise: number of palm prints0 håndflader

Giver

Burnt skin in total4.5 %
Heraf sma pletter (handfladereglen)0 %
Of which from body parts (rule of nines)4.5 %

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Sådan bruger du den

Ved en forbrænding skal du køle og ringe 112, når den er stor. Vagtcentralen spørger, hvor stor den er. 9-reglen og håndfladereglen giver et hurtigt tal i procent af kroppen.

Step by step

Vælg voksen eller lille barn.
For hver kropsdel: skøn hvor stor en del der er forbrændt.
Små pletter: tæl dem i den tilskadekomnes håndflader.
Læs procenten af og sig den til 112.

Typical errors

At bruge din egen hånd i stedet for den tilskadekomnes.
At regne rødme med. Kun blærer og sår tælles.
At bruge voksenreglen på et lille barn. Barnets hoved er større.

Examples from everyday life

Skoldning af underarm og hånd

En kollega har fået kogende vand over højre underarm og hånd. Det er ca. halvdelen af den ene arm, altså en fjerdedel af begge arme.

The injured person: Adult or larger child (head 9 %, each leg 18 %)
Head and neck: part that is burnt: 0 %
Both arms combined: share that is burnt: 25 %
Body front (chest and abdomen): part that is burnt: 0 %
Body back (back and buttocks): part that is burnt: 0 %
Both legs combined: share that is burnt: 0 %
Small patches otherwise: number of palm prints: 0 håndflader

It means: Forbrændingen er ca. 4.5 % af kroppen.

Lille barn skoldet med te

Et lille barn har trukket en kop te ned. Halvdelen af brystet og maven er skoldet, og lidt af armene, ca. 10 % af begge arme.

The injured person: Small child (head 18%, each leg 13.5%)
Head and neck: part that is burnt: 0 %
Both arms combined: share that is burnt: 10 %
Body front (chest and abdomen): part that is burnt: 50 %
Body back (back and buttocks): part that is burnt: 0 %
Both legs combined: share that is burnt: 0 %
Small patches otherwise: number of palm prints: 0 håndflader

It means: Det er ca. 10.8 % af barnets krop. Ring 112.

Små brandsår efter svejsning

En svejser har fået gnister ind under tøjet og har brandsår på brystet, der tilsammen svarer til ca. 3 af hans håndflader.

The injured person: Adult or larger child (head 9 %, each leg 18 %)
Head and neck: part that is burnt: 0 %
Both arms combined: share that is burnt: 0 %
Body front (chest and abdomen): part that is burnt: 0 %
Body back (back and buttocks): part that is burnt: 0 %
Both legs combined: share that is burnt: 0 %
Small patches otherwise: number of palm prints: 3 håndflader

It means: Det er ca. 3 % af kroppen.

Rule of thumb

Den tilskadekomnes håndflade med fingre er ca. 1 % af kroppen.

How to check the answer

Et helt ben hos en voksen er 18 %. Hele kroppen er 100 %.