5 to 8 cm. According to DouDing.com, the diameter of the filling size of the dumplings produced in a dumpling machine is 5 to 8 cm, so the diameter of the filling pipe is 5 to 8 cm. dumpling machine is also known as dumpling machine, dumpling machinery, dumpling machine. The main point is to put the well-mixed dough and the well-tuned filling into the designated feeding port of the machine, and then turn on the machine to produce the finished dumplings.