Abstract: A portable jig for cutting a plurality of building materials quickly, uniformly and accurately, which may be quickly assembled and reassembled for easy transport and maintenance. The jig includes a platform, a deck, a deck fence, an optional platform fence, and two rails. The rails are removably and securably connectable to the fixed platform and passable through the deck, such that both rails are separated from each other. The deck fence is reversibly joinable to the deck. When the platform fence is included, the platform fence is reversibly joinable to the platform. While building materials are laid upon the jig for cutting, a cutting device, such as a circular saw blade, may be passed near and along either of the deck or platform fences to effect this cutting of one or both ends of the building materials. The jig further includes an optional support member for supporting the jig when it is being used.