The coal tit is 10–11.5 cm in length, and has a distinctive large white nape spot on its black head. The head, throat and neck of the adult are glossy blue-black, setting off the off-white sides of the face (tinged grey to yellow depending on subspecies) and the brilliant white nape; the white tips of the wing coverts appear as two wingbars. The underparts are whitish shading through buff to rufous on the flanks. The bill is black, the legs lead-coloured, and irides dark brown.