Adult specimens of the speckled kingsnake, L. g. holbrooki, are the smallest race at 91.5 cm (36.0 in) in snout-to-vent length (SVL) on average, while the nominate race, L. g. getula, is the largest at 107 cm (42 in) SVL on average. Specimens up to 208.2 cm (82.0 in) in total length (including tail) have been recorded. Weight can vary from 285 g (10.1 oz) in a small specimen of 87.2 cm (34.3 in) in total length, to 2,268 g (80.0 oz) in large specimens, of over 153 cm (60 in) in total length.
The color pattern consists of a glossy black, blue-black, or dark brown ground color, overlaid with a series of 23-52 white chain-like rings. King snakes from the coastal plain have wider bands, while those found in mountainous areas have thinner bands or may be completely black.