A gate for a deck railing is made with composite rails that match the profile and height of the composite rails of the deck railing where the gate is being used. The gate includes a pair of spaced side rails that securely support mounts that fit within the ends of the top and bottom composite rails. In some configurations, a cross brace is used from the top of the side rail with the hinges to the bottom of the other side rail. The gate is assembled from a gate kit that allows the user to provide lengths of the composite deck railings to be used as the top and bottom rails in the gate at locations that match the deck railing in order to provide a strong, durable deck gate that blends in with the deck railing.