Fantails, also known as "wagtail flycatchers," vary in length from 5.5 to 8.5 inches (14 to 21.5 centimeters), with weights between 0.2 to 0.9 ounces (6 to 25 grams). These small birds get their name from their long, rounded, fan-shaped tail, often encompassing as much as 50 percent of the bird's total length. Their characteristic flat, triangular bill is common to most flying insectivores, insect eaters. Wide bristles surround the bill in an unusual arrangement of double rows. Most fantails have small feet, except for those more terrestrial, land-dwelling, species. Wings are somewhat rounded, causing the fantails to fly slower but making it easier to maneuver.
Fantails do not usually have bright plumage, feathers, with brown, rust, white, gray, black, or a combination of these, dominating the color scheme. Two species that inhabit the northwestern and western boundaries of the family's distribution area are the exception. The black-cinnamon fantail with its bold, contrasting colors also proves to be an exception. Most males and females are alike in their plumage, though the black fantail of New Guinea has black males and rust-colored females. Another New Guinea species, the dimorphic fantail also shows two colors: one phase is dark, with the black and rust tail; the other shows a light gray tail. Little difference exists between adults and juveniles except that the juveniles' colors are more faded with rusty edges to some of their feathers, especially the wing coverts, feathers that cover the primary flight feathers. Overall, there is a wide variety of color spread throughout the species that are found over a number of islands.