The yellow-bellied sapsucker has a length of around , and an average weight of , although this can range anywhere from . The yellow-bellied sapsucker has a wingspan that ranges from 34-40 cm (13.4-15.8 in). The forehead is coloured bright red in the male (and very occasionally yellow), and a lighter shade of red in the female. Sometimes, this is the only place on the head a female will have red colouration, if it has any at all, as the female rarely has a black head with a few buff spots. The crown is bordered black, and is usually red, and is sometimes mixed with black in the female. There is a white stripe, starting above the eye, that extends and widens to the nape, being broken up by a thin black line on the hindneck. There is a broad black stripe going through the ear-coverts and down to the side of the neck. Below this black stripe is a white stripe that goes from the nasal tufts to the side of the breast. The throat and chin can be used to differentiated between the sexes, as they are white in the female, and red in the male.