The Lapland longspur is about six and one-quarter inches in length. The breeding male has a black face highlighted with a white zig-zag mark and rust-red on the back of the head. The breeding female's colouration resembles the non-breeding male (few black streaks on sides, patch of rust-red on back of head). All colouration phases include red-brown wing coverts and a triangular white patch on each side of the tail base.