Abstract: An adjustable template for defining outer peripheral dimensions of a door comprises first and second side elements (5,6), each of which comprises an outer telescoping member (8) and an inner telescoping member (9). The first and second side elements (5,6) are coupled together by upper and lower linkage mechanisms (10,11) so that the first and second side elements (5,6) are operable between an inoperable state illustrated in FIG. 1 and an operable state illustrated in FIGS. 2 and 3 whereby the first and second side elements (5,6) define the width dimensions of the opening in which the door is to be located from the top of the opening to the bottom of the opening. The inner telescoping members (9) are urged outwardly of the outer telescoping members (8) so that the first and second side elements (5,6) extend from the saddle or floor of the opening of the door to the upper edge of the opening of the doorway.