True regarding thermal injury is all except
Rule of nine (Wallace's formula) is used to calculate the area of burn in adults and the Lund-Browder chart is used in children. 
Burn index combines depth and area to gain insight into prognosis and effectiveness of treatment. 
In child below 5 years, genital form 0% and head forms maximum area in children.
Rule of nines
Lund-Browder chart
Burn index combines depth and area
In child below 5 years, genitals form 1% of area