Abstract: A square for use in pipefitting having a plurality of markings disposed along edges thereof, each of the markings having numeral indicia associated therewith corresponding to an actual conventional pipe size. In particular, the numeral indicia correspond to conventional pipe sizes 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 24, and 30. One of the square tongue edges has markings with numerical degree indicia associated therewith, each of the markings including a line disposed at a numerically indicated angle .alpha. with respect to an edge of the body, all the lines intersecting the body edge at a common apex point. The square can be utilized for a plurality of pipefitting functions, and eliminates the need for complicated calculations, the square providing for readoff of the desired values.