Among wild bovids the gaur is the heaviest and tallest. Mature bulls commonly reach around one hundred and seventy to two hundred and twenty centimetres at the shoulder, with weights that in large individuals exceed a tonne; cows are appreciably smaller. Comparisons with bison depend on whether one counts the largest recorded individuals or typical adults, but by shoulder height the gaur leads.
The dorsal ridge is formed by elongated vertebral spines over the shoulders, giving the profile a distinct step that drops abruptly at mid-back. The white lower legs are consistent enough to serve as a field mark, and both sexes carry horns curving upward and inward from a pale grey boss.
The domesticated form, called the gayal or mithun, is kept in northeastern India and adjacent regions and is usually treated as a domestic derivative of the gaur rather than a separate species. Wild gaur numbers have declined across much of the range, and the species is listed as Vulnerable, with fragmentation of forest a leading pressure.