the plume-toed swiftlet is in length with a square tail. the back and upper surface of the wings are uniformly dark greenish-blue with a moderate gloss. the throat and upper breast are dark grey merging into large greyish chevrons over the lower breast and flanks, usually becoming white over the belly. there is a tuft of small feathers on the , the rear facing toe. this species lacks a pale contrasting rump and has no white spots on the inner webs of the tail feathers.