---
title: "What G-Code Is on the NIMS CNC Mill Test? The Likely Scope"
description: "The G-code a NIMS CNC milling credential expects is the standard mill set: motion, plane and units, offsets, compensation, and basic canned cycles. Here is the list to study."
url: https://gcodepractice.com/journal/what-g-code-is-on-the-nims-cnc-mill-test/
canonical: https://gcodepractice.com/journal/what-g-code-is-on-the-nims-cnc-mill-test/
author: "Lawrence Arya"
authorUrl: https://www.linkedin.com/in/vibecoding/
published: 2026-06-02
updated: 2026-06-02
category: "Practice"
tags: ["nims", "mill", "g-code", "test prep"]
lang: en
---

# What G-Code Is on the NIMS CNC Mill Test? The Likely Scope

> **TL;DR** A NIMS CNC milling credential expects fluency with standard milling G-code: the motion codes (G00 to G03), plane select (G17), units (G20/G21), positioning (G90/G91), work offsets (G54 to G59), tool length and cutter compensation (G43, G40 to G42), reference return (G28), and common canned cycles like drilling (G81). Confirm the exact scope against current NIMS standards; this is the realistic study list, not the actual exam.

A NIMS CNC milling credential does not test obscure codes. It tests whether you can read a standard mill program, which means a focused, predictable set of G-code. Here is the realistic scope to study. Always confirm the exact requirements against the current NIMS standards, since credentials are revised over time, and treat this as a study list, not the actual exam.

## The standard mill set

| Code | Meaning | Why a mill test expects it |
| --- | --- | --- |
| `G00` / `G01` | Rapid / linear feed | Every positioning and cutting move |
| `G02` / `G03` | Clockwise / counterclockwise arc | Contours and radii |
| `G17` | XY plane select | The default milling plane |
| `G20` / `G21` | Inch / millimeter units | Units awareness |
| `G90` / `G91` | Absolute / incremental | Positioning mode |
| `G54`-`G59` | Work coordinate offsets | Where part zero is set |
| `G43` | Tool length compensation | Z handling per tool |
| `G40`-`G42` | Cutter compensation off/left/right | Contour accuracy |
| `G28` | Reference (home) return | Safe machine moves |
| `G81` | Drilling canned cycle | An everyday milling operation |

## How deep to go

For the motion and setup codes, you should recall them instantly and explain what they do in a program. For canned cycles like `G81`, know what the cycle does and the role of its parameters, even if you would look up exact syntax on the job. The credential is checking practical reading fluency, not memorization of every parameter.

## Drill the set for recall

This is a finite, knowable list, which makes it perfect for recall practice. Drill the [common G-codes](/journal/common-g-codes-for-cnc-beginners/) first, get the [modal behavior](/journal/modal-vs-non-modal-g-codes/) right (offsets and positioning modes are modal), and use the method in [beginner CNC code practice](/journal/beginner-cnc-code-practice/). For the broader credential, see [the NIMS CNC operator test guide](/journal/nims-cnc-operator-test-questions-and-answers/). A free tool like [G-Code Sprint](/g-code-practice/) drills the mill set for fast recall.

## Bottom line

The G-code on a NIMS mill test is the standard milling set: motion, plane, units, positioning, offsets, compensation, reference return, and basic canned cycles. Learn that finite list cold and confirm the scope against current NIMS standards.

## Sources

- [NIMS (National Institute for Metalworking Skills)](https://www.nims-skills.org/)
- [LinuxCNC G-code reference (mill codes, canned cycles)](https://linuxcnc.org/docs/html/gcode/g-code.html)
- [CNCCookbook: G-code and M-code cheat sheet](https://www.cnccookbook.com/g-code-m-code-cnc-list-cheat-sheet/)

## Frequently asked questions

### What G-codes should I know for a CNC mill certification?
The standard mill set: `G00` to `G03` for motion, `G17` for the XY plane, `G20`/`G21` for units, `G90`/`G91` for positioning, `G54` to `G59` for work offsets, `G43` for tool length and `G40` to `G42` for cutter compensation, `G28` for reference return, and common canned cycles like `G81` drilling.

### Does a NIMS mill test include canned cycles?
Milling credentials commonly expect awareness of basic canned cycles such as drilling (`G81`) and related cycles, since they are everyday milling operations. Confirm the exact scope against the current NIMS standards for your credential.

### What is the best way to learn the mill G-codes for a test?
Drill them for recall, not recognition. A free tool like G-Code Sprint quizzes the common mill G-codes both directions and repeats the ones you miss, so reading a mill program becomes automatic.

*G-Code Sprint is a study and practice tool only. It is not affiliated with NIMS and does not provide official exam content. Always follow your instructor, employer, machine manual, and shop safety procedures.*

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Source: https://gcodepractice.com/journal/what-g-code-is-on-the-nims-cnc-mill-test/
Author: Lawrence Arya — https://www.linkedin.com/in/vibecoding/