What is the MIN file format?
A .min file is a CNC part program written for Okuma machine tools running the OSP (Open System Platform) controller. The file contains plain ASCII text instructions - G-codes, M-codes, and Okuma-specific macro cycles - that define tool paths, spindle speeds, feed rates, and coordinate movements for machining operations.
The format follows the general structure of ISO 6983 G-code: programs typically begin with a % delimiter or a program number such as O1234, followed by sequential blocks of commands. Okuma's OSP controllers (including the OSP-P300 and OSP-U100/200/300 series) support standard G-code alongside proprietary Okuma macro cycles and canned routines that differ from generic ISO G-code, making direct exchange with non-Okuma machines require translation.
Because .min is plain text, any text editor can technically open and modify these files, but professional CNC editing software such as CIMCO Edit provides critical workflow tools: syntax highlighting, backplotting (2D/3D tool-path visualization), and machine simulation specific to Okuma controllers.
The .min extension is Okuma-specific and should not be confused with a Windows shortcut backup file (also sometimes .min) or with minified JavaScript, which uses the .min.js double extension. Related CNC formats include .nc (generic ISO G-code), .tap, and .cnc - all plain-text variants used by different machine tool brands and controllers.
Security & safety
RISK: LOWMIN files are plain ASCII text and cannot be executed directly by a PC OS. Risk is limited to incorrect machining: a malformed program loaded onto a live CNC machine can cause tool crashes, part damage, or machine damage. Always verify via backplot before running on the machine.
Format details
in a nutshell- Minified JavaScript/CSS file - .min.js and .min.css (doubly-suffixed) are minified web assets; a bare .min extension is rare but occasionally used by build tools for a minified output file.
- Minute Maker file (db_name) - The database incorrectly names this 'Minute Maker file'; Okuma CNC Program File is the correct and dominant identity for .min.
Programs that open MIN files
Windows3 apps
CIMCO Edit
Paid File → Open, navigate to the .min file; use F5 for backplot simulation, Machine Simulation tab for full 3D collision check with Okuma machine models. 
Notepad
Open-source Open with Notepad++; install a G-code syntax highlighting plugin (UDL) for readability.
Notepad (built-in)
Built-in Right-click the .min file → Open with → Notepad. No syntax highlighting; for viewing only. Technical details
deep spec| File type | Plain-text CNC G-code part program |
| Encoding | ASCII text |
| Controller platform | Okuma OSP controllers (OSP-P300, OSP-U100/200/300 series) |
| Program header | Begins with `%` delimiter or program number (e.g. `O1234`) per G-code convention |
| Instruction types | G-codes (geometry/motion), M-codes (machine functions), Okuma macro cycles |
| Okuma-specific features | Proprietary macro cycles and canned routines that differ from standard ISO 6983 G-code |
| Typical size | 1 KB - 500 KB (simple parts to complex multi-axis programs) |
| Associated OS | Windows (CNC editing software) |
| Professional editor | CIMCO Edit - syntax highlighting, backplotting, Okuma simulation |
| Related formats | .nc (generic ISO G-code), .tap, .cnc |
| Extension ambiguity | Not related to Windows shortcut backups or .min.js (minified JavaScript) |
| Output controls | Tool path, spindle speed (S-code), feed rate (F-code), coolant (M08/M09), axis coordinates |
| Released | 1990s (Okuma OSP CNC controller systems) |
MIN conversions
Community Q&A
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