STLPalGuides / Updated October 10, 2026
3MF vs STL: which one should you use?
Use 3MF when you can, and STL when something only takes STL. 3MF holds the shape plus the unit, colours, parts and settings. STL holds the shape only.
What is a 3MF file?
3MF (3D Manufacturing Format) is a newer file for 3D printing, from the 3MF Consortium, a group started in 2015 by Microsoft and other companies. A 3MF is a zip file. Inside is the model written as text, plus room for extras.
Bambu Studio and PrusaSlicer save their projects as 3MF, which is why MakerWorld downloads come that way.
Side by side
| STL | 3MF | |
|---|---|---|
| Shape | Yes | Yes |
| Unit (mm, inch…) | No, slicers guess mm | Yes, written in the file |
| Several parts in one file | No | Yes |
| Colours and materials | No | Yes |
| Slicer settings, plates | No | Yes, if the slicer saved them |
| File size | Larger | Smaller (shared corners, zipped) |
| Opens almost everywhere | Yes | Most slicers, fewer other tools |
3MF does everything STL does and more. STL wins only on how many programs can open it.
Which to use
- Sharing a print with its settings, or a multi-colour model: 3MF.
- Sending a file to a print service or an older tool: STL, unless they say they take 3MF.
- Editing the design later in CAD: neither. Keep the original CAD file (or STEP), because both 3MF and STL are just triangles.
Switching between them
Going from 3MF to STL keeps the shape and drops the colour, settings and part layout. Going from STL to 3MF adds the unit and lets you pack several parts into one file. Both converters below run in your browser.