<prompt> When a palm is used as a measuring scale in estimating the burnt area, it is equal to1 of body surface area3 of body surface area4.5 of body surface area9 of body surface area  <response>: Rule of palms: The surface area of a patients palm including fingers is roughly 1 of TBSA. Palmar surface can be used to estimate small burns 15 TBSA or very large burns 85, when unburnt skin is counted. Ref - Srbs manual of surgery 5th edition , burns 