In breeding season, the adult male shelduck has a white body with a chestnut band from its upper back to its lower breast, and a black band along the centre of its belly.

The wings have black and glossy green edges forming long dark bands along its back when on water. The tail is white with chestnut underneath and a black tip.

The head is a black with a dark green glossy sheen. The bill is bright red with a large knob at the base, the eyes are dark brown, and the legs and feet are pink.

The female is like the male, except she is duller overall and has a narrower breast band, and white patches on the face.

In winter, the shelduck has greyer plumage with white markings on the breast band and brown edges on the feathers.

Juvenile shelducks are similar to adults in non-breeding plumage, but the face is white, and the bill, legs, and feet are grey.