RULE OF NINE
It is not only the thickness, but also the extent of the burn that determines its seriousness. If the burn covers a large surface area, the victim will undergo a critical stage due to loss of fluids.
The extent of the burn is easy to determine with Wallace's "rule of 9'. Here, the total body surface is divided into units which are multiples of 9.
Useful information: the palm of your hand (with fingers closed) represents approximately 1% of your total body surface.
In children, the head is relatively larger than the rest of the body, and can therefore represent 19 % of a one year old's body surface.
It is also important to differentiate between the varying thicknesses of the burns in order to determine their extent.