Abstract: A carpenter's tool expedites the cutting of lengthy boards into shorter segments of uniform length with a hand held power saw or the like. The angled tool has a linear board guide member that is abutted against a side of the board and a saw guide member which extends across the board and defines a surface along which the saw may be traveled. A stop member extends from the board guide member for abutment against the end of the board to to fix the length of the segments which are cut from the board, the position of the stop member along the board guide member preferably being adjustable. The hand of the operator which grasps the board guide member during a cutting operation is held at a location away from the saw by a thumb grip which extends between the operator's thumb and forefinger. The tool may also be provided with rulings for measuring distances in a building framework or the like that are to be spanned by the board segments.