# 3MF to STL Converter

> To convert 3MF to STL, open the .3mf in a converter that reads 3MF packages and export its mesh as an STL file. Kenerate's free converter does it in your browser without uploading the file: drop it, preview it, optionally set the longest side in millimetres and download a binary STL. Colours and print settings are dropped.

URL: https://kenerateai.com/3mf-to-stl
Publisher: Kenerate AI (https://kenerateai.com)
Last updated: 2026-10-01

## Key facts
- Price: Free, no account
- Converts: 3MF (3D Manufacturing Format) package → binary STL
- Kept: Geometry of every object on the build plate
- Dropped: Colours, materials, print settings, plate layout
- Scale: Keep the file's units or fit longest side to 25–200 mm
- Privacy: Converted locally — no upload
- STL opens everywhere: Older slicers, printer firmware tools, CAD imports and print services that only take STL get a file they can read.
- Check it first: The 3D preview shows the model before you download — no surprises after a long upload to a print service.
- Millimetres preserved: 3MF stores real units; the converter keeps that size in the STL coordinates, or rescales to the size you choose.
- Ready for slicers: Z-up is on by default, matching how slicers and CAD tools orient a print.
- Unzip: The 3MF package is opened and its 3D/3dmodel.model XML is read.
- Build: Every object and its transform on the build plate become meshes in millimetres.
- Orient: The model is turned Z-up for slicers and optionally resized to your chosen length.
- Write: All triangles are written to one binary STL and downloaded.
- 3MF (3D Manufacturing Format): ZIP package with XML; by 3MF Consortium, 2015. Holds: Meshes with units (millimetres), Colours and materials, Several objects and build plates. Lacks: Animation. Best for: Modern 3D printing and multi-colour prints. Opens in: Bambu Studio, PrusaSlicer, OrcaSlicer, Cura, Windows 3D Builder.
- STL (Stereolithography): Triangle mesh (binary or ASCII); by 3D Systems, 1987. Holds: Triangle surfaces, Facet normals. Lacks: Colour and textures, Units, Materials. Best for: 3D printing — every slicer opens it. Opens in: Cura, PrusaSlicer, Bambu Studio, OrcaSlicer, Blender.
- Units — 3MF vs STL: Stored in the file (millimetres by default) | None — slicers assume millimetres
- Colour and materials — 3MF vs STL: Yes, per object or per triangle | No
- Several objects / plates — 3MF vs STL: Yes, with positions | One triangle list
- Print settings — 3MF vs STL: Slicers can embed them | No
- File size — 3MF vs STL: Compressed ZIP — usually smaller | Uncompressed — usually larger
- Support — 3MF vs STL: Modern slicers | Practically every 3D tool

## Steps
1. Open the 3MF — Drop your .3mf onto the box above, or try the sample dragon.
2. Check the preview — Orbit the model and check its triangle count and size.
3. Pick STL — STL is selected. Keep units, or fit the longest side to a size in millimetres.
4. Download — Click Download STL. The file is saved straight to your device.

## In depth

### What is inside a 3MF
3MF is published by the 3MF Consortium, founded in 2015 by companies including Microsoft, Autodesk, HP and Shapeways [5]. A .3mf file is a ZIP package holding an XML model with vertices, triangles and a unit, plus optional colours, materials, thumbnails and slicer metadata [5].

### When to keep 3MF instead
For multi-colour prints, several parts with set positions, or sharing a project with its settings, keep 3MF — modern slicers like Bambu Studio, PrusaSlicer, OrcaSlicer and Cura read it [5]. Convert to STL only when a tool can't.

### If the STL looks wrong
If parts are missing, the 3MF may use components or a newer extension the reader doesn't support. Export a plain 3MF or STL directly from the slicer that made it.

References:
[1] Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)
[2] Wikipedia — Wavefront .obj file: https://en.wikipedia.org/wiki/Wavefront_.obj_file
[3] Wikipedia — FBX: https://en.wikipedia.org/wiki/FBX
[4] Khronos Group — glTF: https://www.khronos.org/gltf/
[5] 3MF Consortium — 3MF specification: https://3mf.io/specification/
[6] Wikipedia — Universal Scene Description (USD / USDZ): https://en.wikipedia.org/wiki/Universal_Scene_Description
[7] Wikipedia — PLY (file format): https://en.wikipedia.org/wiki/PLY_(file_format)
[8] Khronos Group — glTF 2.0 specification: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html
[9] Apple — AR Quick Look: https://developer.apple.com/augmented-reality/quick-look/
[10] three.js — documentation: https://threejs.org/docs/
[11] Prusa Knowledge Base — Modeling with 3D printing in mind: https://help.prusa3d.com/article/modeling-with-3d-printing-in-mind_164135
[12] Prusa Blog — lithophanes and filament transparency: https://blog.prusa3d.com/lets-play-with-filament-transparency-how-to-make-amazing-lifelike-color-photos-with-just-a-simple-color-change_104338/
[13] Polymers (2024) 16(20):2862 — FFF parameters and translucency of PLA: https://doi.org/10.3390/polym16202862
[14] Wikipedia — Lithophane: https://en.wikipedia.org/wiki/Lithophane
[15] W3C — CSS Values and Units Level 3 (absolute lengths): https://www.w3.org/TR/css-values-3/
[16] Adobe Substance 3D — OpenGL vs DirectX normal maps: https://experienceleague.adobe.com/en/docs/substance-3d/bakers/common-questions/what-is-the-difference-between-the-opengl-and-directx-normal-format
[17] Blender Manual — Normal Map node: https://docs.blender.org/manual/en/latest/render/shader_nodes/displacement/normal_map.html
[18] Wikipedia — Normal mapping: https://en.wikipedia.org/wiki/Normal_mapping
[19] SIL Open Font License: https://openfontlicense.org/

## FAQ
Q: Is the 3MF to STL converter free?
A: Yes. Free, no account and no watermark — the conversion runs in your browser.

Q: Is my 3MF uploaded?
A: No. It's unzipped and converted on your device.

Q: Will I lose colours?
A: Yes. STL has no colour, so multi-colour or multi-material information is dropped. Keep the 3MF for colour printing.

Q: What about several objects on the plate?
A: They're merged into one STL in their plate positions. To print them separately, split them in your slicer.

Q: Will the size change?
A: No, unless you choose a size. 3MF is in millimetres and the STL coordinates keep those values.

Q: Do my print settings carry over?
A: No. Settings and profiles embedded by Bambu Studio or PrusaSlicer stay in the 3MF; STL can't hold them.

Q: Can I extract an STL from a Bambu Studio or PrusaSlicer 3MF project?
A: Yes. Drop the project .3mf here: every object on the plate is written into one STL in its plate position, while colours, painted supports and print settings stay in the 3MF. If you only need one part, delete or split the others in your slicer first.

Q: Can I go the other way?
A: Yes — use the STL to 3MF converter to add units and a modern format.

## Related pages
- AI 3D Model Generator: https://kenerateai.com/ai-3d-model-generator
- Image to 3D: https://kenerateai.com/image-to-3d-converter
- AI STL Generator: https://kenerateai.com/ai-3d-printing-model-generator
- Text to 3D: https://kenerateai.com/text-to-3d-generator

## Sources
- Wikipedia — STL (file format): https://en.wikipedia.org/wiki/STL_(file_format)
- Wikipedia — Wavefront .obj file: https://en.wikipedia.org/wiki/Wavefront_.obj_file
- Wikipedia — FBX: https://en.wikipedia.org/wiki/FBX
- Khronos Group — glTF: https://www.khronos.org/gltf/
- 3MF Consortium — 3MF specification: https://3mf.io/specification/
- Wikipedia — Universal Scene Description (USD / USDZ): https://en.wikipedia.org/wiki/Universal_Scene_Description
- Wikipedia — PLY (file format): https://en.wikipedia.org/wiki/PLY_(file_format)
- Khronos Group — glTF 2.0 specification: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html
- Apple — AR Quick Look: https://developer.apple.com/augmented-reality/quick-look/
- three.js — documentation: https://threejs.org/docs/
- Prusa Knowledge Base — Modeling with 3D printing in mind: https://help.prusa3d.com/article/modeling-with-3d-printing-in-mind_164135
- Prusa Blog — lithophanes and filament transparency: https://blog.prusa3d.com/lets-play-with-filament-transparency-how-to-make-amazing-lifelike-color-photos-with-just-a-simple-color-change_104338/
- Polymers (2024) 16(20):2862 — FFF parameters and translucency of PLA: https://doi.org/10.3390/polym16202862
- Wikipedia — Lithophane: https://en.wikipedia.org/wiki/Lithophane
- W3C — CSS Values and Units Level 3 (absolute lengths): https://www.w3.org/TR/css-values-3/
- Adobe Substance 3D — OpenGL vs DirectX normal maps: https://experienceleague.adobe.com/en/docs/substance-3d/bakers/common-questions/what-is-the-difference-between-the-opengl-and-directx-normal-format
- Blender Manual — Normal Map node: https://docs.blender.org/manual/en/latest/render/shader_nodes/displacement/normal_map.html
- Wikipedia — Normal mapping: https://en.wikipedia.org/wiki/Normal_mapping
- SIL Open Font License: https://openfontlicense.org/