Long-tailed widowbirds exhibit distinct sexual dimorphism. Males and females exhibit differences in behavior and morphological traits. Adult males are entirely black, including under their wing-coverts. Males' wing shoulders are orange red and their wing-coverts white. Their bills are bluish white. Males are known for their distinctly long tails, which contain twelve tail feathers. Of these twelve tail feathers, between six and eight are approximately half a metre (approximately 20 inches) long. Males have wingspans of approximately 127 to 147 mm (approximately 5 to 5.8 inches).