The red-necked grebe is a medium-large grebe, smaller than the great crested grebe of Eurasia, and the western and Clark's grebes of North America, but noticeably larger than other northern grebe species. The adult of the nominate European subspecies is long with a average wingspan, and weighs . In breeding plumage, it has a black cap that extends below the eye, very pale grey cheeks and throat, a rusty red neck, dark grey back and flanks, and white underparts. The eyes are dark brown and the long, pointed bill is black with a yellow base.