LinuxCNC G43

G43 is a LinuxCNC G-code that enables tool length compensation. It offsets subsequent axis coordinates by the stored tool length and does not cause motion; the next compensated axis move uses the compensated endpoint. G43 without H uses the currently loaded tool from the last Tn M6, while G43 Hn uses the offset for tool n.

Source checked5/5 values · 2026-10-26

Specification

1 source

Language	gcode
Code	G43
Group	Tool Length Offset
Syntax	G43 <H->
Dialect	LinuxCNC

Parameters

Name	Description
H	tool number (optional)

Study notes

G43 does not cause any motion.
The tool length compensation values applied to motion are stored in numbered parameters 5081-5089.
Parameters 5401-5409 hold the loaded tool's stored offset and are refreshed on tool change (M6) and G10 L1/L10/L11.
G43 H0 behavior differs by tool changer: on nonrandom changers it applies the current spindle tool's TLO or 0 if no tool is loaded; on random changers it applies T0 from the tool table or errors if T0 is undefined.
It is an error if the H number is not an integer, is negative, or is not a valid tool number; 0 is a valid tool number on nonrandom tool changer machines.