How to open .CGM files on Mac
To open .CGM files on Mac, if double-clicking does not work, open your graphics/CAD or technical illustration tool and use File → Open/Import to select the .cgm file.
Step-by-step instructions
- If double-clicking does not work, open your graphics/CAD or technical illustration tool and use File → Open/Import to select the .cgm file.
- If you don’t have CGM-capable software on macOS, transfer the file to a desktop environment where CGM is supported in your workflow, then export to a more common sharing format.
Recommended software
- Preview
- Photos
- GIMP
Alternative methods
- Open .CGM in a browser-based viewer if desktop apps fail.
- Try opening .CGM on Mac with a secondary app to rule out app-specific issues.
- Convert .CGM only with trusted tools when direct opening is not possible.
Common issues
The file won’t open or shows as an unknown format
CGM is a specialized ISO standard and many general-purpose image viewers don’t support it. The issue is usually missing CGM support rather than a bad file.
- Open the file from inside a CGM-capable application using an Import/Open command (don’t rely on double-click association).
- Try opening it in the same environment/workflow that produced it (common in technical illustration and SAP-related documentation workflows).
- If you only need to share it, export/convert from a CGM-capable tool to a more widely supported format.
Opens, but graphics look wrong or elements are missing
Different tools may implement different CGM parts/profiles; complex CGM features (mixed vector/raster/text, specific attributes) may not render identically everywhere.
- Try a different CGM-capable application (or the original creator tool) to compare rendering.
- If you control the export, re-export using a simpler CGM option/profile if available, or export to another interchange format for recipients.
File extension and MIME/type detection problems
Some systems rely on MIME mappings (e.g., image/cgm) and file associations; if misconfigured, the OS won’t know what to do with .cgm files.
- Ensure the file really is a CGM and still has the .cgm extension.
- On Linux desktops, verify your environment recognizes image/cgm and associate it with your chosen CGM-capable application.
- Use the application’s File → Open/Import rather than relying on the OS association.
Security note
CGM files are graphics metafiles (image/cgm), not executables, but they can be complex to parse; only open CGM files from sources you trust to reduce the risk of exploiting bugs in viewers/importers.