The barnacle goose is a medium-sized goose, 55–70 cm long, with a wingspan of 130–145 cm and a body mass of 1.21–2.23 kg. It has a white face and black head, neck, and upper breast. Its belly is white. The wings and its back are silver-gray with black-and-white bars that look like they are shining when the light reflects on it. During flight a V-shaped white rump patch and the silver-gray underwing linings are visible.