Miter Description base on ASME B31.3: two or more straight sections of pipe matched and joined in a plane bisecting the angle of junction so as to produce a change in direction. Elbow is one of most useful Fittings in Piping Industries that have many Types. Elbows are not made in Greater than 20 inches as usual. In these cases for changing of direction of Pipe, Miter is fabricating. Everyone in Piping Industries Knows about Miters but designing of Flat Pattern of Miter always was a problem. Because of it, we decided to develop this app for designing Flat Pattern of Miter that Piping Engineers,Technical Officers, Construction Supervisors, QC Inspectors, Fitters and etc., could use this App.