Set units to inches.
G20 is a G-code used to set the units of measurement to inches. It is used to specify that all coordinates in the G-code program are to be interpreted as inches. This is typically used in CNC machines that are used in the United States and other countries that use the imperial system of measurement.
G21 is the counterpart of G20 command, it is used to set the units of measurement to millimeters. This is typically used in CNC machines that are used in countries that use the metric system of measurement.
For example, if a G-code program starts with G20 all the following coordinates will be in inches, while if it starts with G21 all the coordinates will be in millimeters.
G20
G20