Quick Reference

A one-page lookup of the most common G-codes, M-codes, and formulas. Use this while working — not while learning. For explanations, follow the links to each topic.

G-Codes

Code	Function	Modal?
G00	Rapid positioning	Yes (motion group)
G01	Linear feed interpolation	Yes
G02	Clockwise circular arc	Yes
G03	Counterclockwise circular arc	Yes
G04	Dwell (P / X seconds)	No (one block)
G17/G18/G19	XY / XZ / YZ plane selection	Yes
G20/G21	Inch / millimeter units	Yes
G40/G41/G42	Cutter comp off / left / right	Yes
G43/G49	Tool length comp on / off	Yes
G53	Machine coordinates (one block)	No
G54–G59	Work coordinate systems	Yes
G70	Finish turning cycle (lathe)	Yes
G71	Rough turning cycle (lathe)	Yes
G76	Threading cycle	Yes
G80	Cancel canned cycle	Yes
G81	Drilling cycle	Yes
G82	Drill with dwell	Yes
G83	Peck drilling cycle	Yes
G84	Right-hand tapping cycle	Yes
G85	Boring cycle	Yes
G90/G91	Absolute / incremental	Yes
G94/G95	Feed per minute / per revolution	Yes
G96/G97	Constant surface speed / fixed RPM	Yes
G98/G99	Cycle retract to initial / R plane	Yes

M-Codes

Code	Function
M00	Program stop (unconditional)
M01	Optional stop (switch-dependent)
M03/M04/M05	Spindle CW / CCW / stop
M06	Tool change (mill)
M08/M09	Coolant on / off
M30	Program end and rewind
M98	Call subprogram
M99	Return from subprogram

Common Formulas

RPM = Vc × 1000 / (π × D)
Feed (mm/min) = fz × flutes × RPM
Feed (mm/rev) = mm/min / RPM
Cutting time = distance / feed
MRR (mm³/min) = width × depth × feed
Tap feed = pitch × RPM
Drill tip height = (D/2) / tan(point_angle/2)

Common Mistakes

This page is intentionally brief. For each code, follow the link to the detailed lesson. M-codes are machine-specific — always verify against your manual.

Quick Self-Test

1. Quick: G83 is what?

Ans

Peck drilling cycle (G83 with Q peck depth).

2. Quick: M08?

Ans

Coolant on.

3. Quick: G41?

Ans

Cutter radius compensation, left side of cut direction.

4. Quick: G96?

Ans

Constant surface speed (CSS) on a lathe — RPM varies with diameter.