A carpet trimmer including a base, a pair of posts mounted on said base and a handle mounted on said base. A number of spacers are inserted over the posts and secured by fasteners. A blade holder holding a pair of blades and including a blade holding face and a wall runner is inserted between two of the spacers, such that the posts fit into groove on the blade holding face. Throat adjustment holes on said spacers receive dimples on the blade holder to allow throat adjustment.