If you don't have a Pipe lofted drawing You can calculate Pipe cutting size using this App without drawing and calculator.

1. Value of Planar figure for Pipe cutting Pipe reducer Ecc reducer.
2. Hole size for Nozzle T fit up Ecc nozzle fit up
3. Y tee Hood duct Elbow support fit up.

But this program is made for the convenience of pipe cutting calculation. Therefore the author is not responsible for possible damage arising as a result of its usage.