Abstract: The present invention relates to a folding chimney flue cap [1000] for fitting chimneys. The folding flue cap [1000] is manufactured as a flat body [1100] having an end panel [1140], a side panel [1160], another end panel [1150], and another side panel [1170], separated by fold lines [1180] between the panels. The folding chimney flue cap [1000] also includes top tabs [1120] above each of these panels. There are also bottom tabs [1130] below each of these panels. The flat body [1100] has a first connector part [1210] at one end and a second connector part [1220] on the other end. The folding flue cap [1000] may be readily shipped in its compact form and assembled into a box shape connecting first connector part [1210] to second connector part [1220]. The top tabs [1120] and the bottom tabs [1130] may be bent either inwardly or outwardly to better match the structures to which it would connect.