Every G Code for Your CNC [The Complete List] - Machinist Guides (2024)

Plane selection affects how G02, G03, cutter compensation and some canned cycles are handled. G18 tells the machine you are machining radii around the Y axis.

G20 - Inch Mode

All size and location commands will be in inches until changed.

Learn more about the G20 code

G21 - Metric Mode

All size and location commands will be in millimeters until changed.

Learn more about the G21 code

G40 - Cancel Cutter Compensation

Turns off any cutter compensation modes (G41 or G42).

Learn more about the G40 code

G41- Cutter Compensation Left

Shifts the machine tool path to the left based on the radius of the cutting tool.

Learn more about the G41 code

G42 - Cutter Compensation Right

Shifts the machine tool path to the right based on the radius of the cutting tool.

Learn more about the G42 code

G43 - Tool Length Compensation

Adjusts a tool’s location based on a specified tool height (H) offset.

Learn more about the G43 code

G49 - Tool Length Compensation Cancel

Turns off the tool length compensation set by a G43 or G44 command.

Learn more about the G49 code

G54 - Work Offset 1

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G54 code

G55 - Work Offset 2

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G55 code

G56 - Work Offset 3

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G56 code

G57 - Work Offset 4

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G57 code

G58 - Work Offset 5

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G58 code

G59 - Work Offset 6

Sets a specific location in the CNC as the zero location for the program.

Learn more about the G59 code

G73 - High-Speed Peck Drilling Canned Cycle

Peck drill a hole by repeatedly drilling, then retracting a small amount, then drilling deeper. Often used to break up chips when drilling.

Learn more about the G73 code

G74 - Left-Hand Tapping Canned Cycle

A tapping cycle for left-hand or reverse threads. The spindle must be running in reverse during this cycle. The machine will feed to the bottom of the hole and then reverse the spindle direction and back out of the hole.

Learn more about the G74 code

G81 - Standard Drilling Cycle

Drills a hole then rapid retracts out of the hole.

Learn more about the G81 code

G82 - Standard Drill with Dwell

Drills a hole, dwells at the bottom of the hole for a set amount of time and then rapid retracts out of the hole.

Learn more about the G82 code

G83 - Deep Hole Peck Drilling Cycle

The machine will drill in pecks while rapid retracting out of the hole between each peck to help clear chips from the drill.

Learn more about the G83 code

G84 - Right-Hand Tapping Cycle

The standard tapping cycle with the spindle running clockwise. The CNC will feed to the bottom of the hole and then reverse the spindle direction and back out of the hole.

Learn more about the G84 code

G85 - Reaming Cycle

The machine will feed to the bottom of the hole and then rapid retract out.

Learn more about the G85 code

G86 - Boring Cycle

The machine will feed to the bottom of the hole and then rapid retract out. The tool is not pulled away from the surface which can leave a tool mark on the hole.

Learn more about the G86 code

Bores a hole from bottom to top. This is the reverse direction of the G86 code.

Turns off scaling mode.

G80 - Canned Cycle Cancel

Cancels any active canned cycles for drilling, boring, tapping, etc.

Learn more about the G80 code

G90 - Absolute Mode

All movement locations are relative to a fixed zero such as the work offset (G54, G55, etc.) or machine home location.

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G91 - Incremental Mode

All movement locations are relative to the machine’s current position.

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The spindle speed will vary to maintain the same surface speed of the material.

G98 - Return to Initial Plane

After a canned cycle the tool will retract to the start of the canned cycle.

Learn more about the G98 code

G99 - Return to Rapid Plane

After a canned cycle the tool will retract to a specified location. Can be useful for avoiding workholding fixtures.

Learn more about the G99 code