An outlet box is configured to be installed to a building structure in a new work or an old work. The outlet box includes an outlet box body and a removable flange partially attached to the outlet box body. The outlet box body has a base member, a first longitudinal side wall, a second longitudinal side wall, a first transverse side wall, and a second transverse side wall. The first and second longitudinal side walls and the first and second transverse side walls are integrally connected to the base member and extend upwardly therefrom, defining an outlet box volume therewithin. A plurality of first angled mounting holes and a plurality of second angled mounting holes are defined on an inner surface of one of the first and second longitudinal side walls and an inner surface of one of the first and second transverse side walls, respectively.