# Displaying millimeters but moving in inches

**URL:** <https://forum.avidcnc.com/t/displaying-millimeters-but-moving-in-inches/2733>\
**Category:** General Chat\
**Created:** [December 13, 2023, 7:00pm UTC](https://forum.avidcnc.com/t/displaying-millimeters-but-moving-in-inches/2733 "2023-12-13T19:00:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![spsie](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/spsie/32/3073_2.png) [@spsie](https://forum.avidcnc.com/u/spsie)\
**Post date:** [December 13, 2023, 7:00pm UTC](https://forum.avidcnc.com/t/displaying-millimeters-but-moving-in-inches/2733/1 "2023-12-13T19:00:11Z")

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Have just finished building a new PRO6060: I have units set to mm in Mach4, but the machine is moving in inches. (i.e., 1mm indicated = 1in of actual movement).

I am sure this is a simple setup issue.

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**Author:** ![Eric](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/eric/32/3220_2.png) [@Eric](https://forum.avidcnc.com/u/Eric)\
**Post date:** [December 15, 2023, 5:59pm UTC](https://forum.avidcnc.com/t/displaying-millimeters-but-moving-in-inches/2733/2 "2023-12-15T17:59:28Z")

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It could be the G Code you’re running, can you post it here?

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**Author:** ![Stephen](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/stephen/32/2569_2.png) [@Stephen](https://forum.avidcnc.com/u/Stephen)\
**Post date:** [December 16, 2023, 2:38pm UTC](https://forum.avidcnc.com/t/displaying-millimeters-but-moving-in-inches/2733/3 "2023-12-16T14:38:32Z")

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To expand on Eric’s comment, your CAD/CAM software might have an option to embed a units selection into the G-code program. If the program contains a “G20” command, then the units will switch to inches and stay there unless/until a “G21” is commanded. From the [Mach 4 G-code milling manual](https://www.machsupport.com/wp-content/uploads/2014/05/Mach4%20Mill%20GCode%20Manual.pdf):

> G20/G21 – Unit selection: Programming units are selected using G20 for inch and G21 for millimeter.  
> Use these G codes to specify the units in the program only; the setting will not affect Mach DRO’s,  
> configuration settings, or offsets.