Q:  What is another rule of thumb in evaluating burn area besides 'rule of 9'?

Answer: The Rule-of-Palms

The patient's palm can serve as a guide roughly equivalent to 1% of the total body surface area (TBSA).

Reference:

Wen-bo Sheng, Ding Zeng, Yan Wan, Li Yao, Hong-tai Tang - BurnCalc assessment study of computer-aided individual three-dimensional burn area calculation - J Transl Med. 2014; 12(1): 242. - Published online Sep 10, 2014.