As with most of the genus "Sillago", the Thai whiting has a slightly compressed, elongate body tapering toward the terminal mouth. The body is covered in small ctenoid scales extending to the two rows of cheek scales and head. The first dorsal fin has 11 spines and the second dorsal fin has 1 leading spine with 21 to 22 soft rays posterior. The anal fin is similar to the second dorsal fin, but has 2 spines with 21 to 22 soft rays posterior to the spines. Other distinguishing features include 67 to 70 lateral line scales and a total of 34 vertebrae. The species has a known maximum length of 20 cm.