Sexes are alike--11 1/2 to 13 1/2 inches long with a wingspread of 21-24 inches. These puffins are short, stocky with upper parts black and undersides white. Their cheeks are white. They have large parrotlike, triangular shaped bills, which in the breeding season are bright orange with a yellow-bordered patch of blue at the rear half. After the breeding season, they lose some of their horny bill plates and molt as well. Winter plumage is similar but faces are largely dark.
Average mass: 490.5 g.