# 3MF vs STL

> Use 3MF when your slicer supports it, because it stores units in millimetres, colours, materials, several objects and slicer settings, usually in a smaller file. Use STL when sharing with older tools, CAD imports or print services that only accept it: every program reads it, but it holds only triangles, with no units or colour.

URL: https://kenerateai.com/3mf-vs-stl
Publisher: Kenerate AI (https://kenerateai.com)
Last updated: 2026-10-02

## Key facts
- Units: 3MF: stored · STL: none
- Colour: 3MF: yes · STL: no
- Multiple objects: 3MF: yes · STL: one mesh
- File size: 3MF usually smaller (ZIP, shared vertices)
- Compatibility: STL: everything · 3MF: modern slicers

## In depth

### Side by side
Created — 3MF Consortium, 2015 [1] — 3D Systems, 1987 [2]
Structure — ZIP package with XML model [1] — List of triangles [2]
Units — Stored, millimetres by default [1] — None — slicers assume mm [2]
Colours, materials — Yes — No
Several objects — Yes, with positions and plates — One triangle soup
Slicer settings — Can be embedded — No
File size — Usually smaller — Larger for the same mesh
Opens in — Modern slicers, Windows 3D Builder — Everything

### When to choose 3MF
- Multi-colour or multi-material prints.
- Projects with several parts arranged on a plate.
- Sharing a print with its settings and supports.
- Avoiding scale mistakes — the unit travels with the file.

### When STL is still better
- Print services and marketplaces that only accept STL.
- Older slicers, firmware tools and some CAD imports.
- Simple single-part prints where colour and settings don't matter.

### Converting between them
STL → 3MF adds a unit and merges repeated vertices, so the file is usually smaller. 3MF → STL keeps the geometry but drops colours, plate layout and settings, because STL has nowhere to put them [2].

References:
[1] 3MF Consortium — 3MF specification: https://3mf.io/specification/
[2] Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)

## FAQ
Q: Is 3MF better than STL?
A: For modern printing workflows, yes — it stores units, colours and multiple objects. STL wins on compatibility.

Q: Is 3MF smaller than STL?
A: Usually. 3MF is compressed and shares vertices between triangles.

Q: Does print quality differ?
A: No — the geometry is the same. Differences come from settings, which 3MF can carry along.

Q: Can every slicer open 3MF?
A: Major modern slicers can. Some older tools and services still need STL.

Q: How do I convert STL to 3MF?
A: Use the free STL to 3MF converter; set a size in millimetres if needed.

Q: Should I download 3MF or STL files?
A: Take the 3MF when a model site offers both and your slicer reads it — you get the designer's units, colours, part layout and often their print settings. Take the STL for older slicers, CAD imports or print services that only accept STL; you'll set the size and settings yourself.

Q: How do I change 3MF to STL?
A: Drop the .3mf into the free 3MF to STL converter, check the preview and download a binary STL. The geometry is kept in millimetres; colours, plate layout and settings are dropped because STL can't hold them. Nothing is uploaded — the conversion runs in your browser.

## Related pages
- STL to 3MF: https://kenerateai.com/stl-to-3mf
- 3MF to STL: https://kenerateai.com/3mf-to-stl
- What is a 3MF file?: https://kenerateai.com/what-is-a-3mf-file
- What is an STL file?: https://kenerateai.com/what-is-an-stl-file

## Sources
- 3MF Consortium — 3MF specification: https://3mf.io/specification/
- Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)