Absolute and Relative Gcode programming modes (Gcode G90 / G91)

G90 vs G91

G90 G91

In all Gcode instructions that follow, the controller will interpret the next coordinate according to the active “Mode”, G90 or G91. The mode will stay in effect until a different G90/G91 will be encountered in the program. The mode will affect any movement commands, such as G00, G01, G02, etc.

  • G90 – Absolute Mode
  • G91 – Relative (Incremental) Mode.


We assume the machine is already positioned at coordinate (1,1). Both program snippets will execute the exact same movements.

Absolute Mode (G90) Example

N10 G90 G00 X5.0  Y3.0;
N20 G00 X6.0 Y5.0;
N30 G00 Y8.0;

Relative Mode (G91) Example

N10 G91 G00 4.0  Y2.0;
N20 G00 X1.0 Y2.0;
N30 G00 Y3.0;

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