Format Guide
3MF file: convert 3MF to STL (and STL to 3MF)
Turn Bambu Studio and PrusaSlicer projects into STL for any tool, or pack STL meshes into 3MF. One file or a whole folder.
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Where this format fits
Your file
Solid CAD
- STEP
- IGES
- BREP
Meshes
- STL
- OBJ
- 3MF
- PLY
- glTF
- GLB
- FBX
- DAE
- X3D
- OFF
- AMF
3D faces in drawings and scenes
- DXF
- DWG
- USD
What you get
3D printing
- STL
- 3MF
- OBJ
- PLY
Web, AR and games
- glTF
- GLB
- FBX
- DAE
Viewers and archives
- VRML
- X3D
- OFF
CAD exchange
- STEP
- IGES
- BREP
Solid CAD (STEP, IGES, BREP) can become a mesh or another solid format. A mesh converts to other meshes. Dashed formats (DXF, DWG, AMF, USD) can be read but not written. VRML reads .wrl, .vrml and gzipped .wrz files and writes .wrl.
- Convert a 2D-only DWG or DXF drawing. It needs 3D faces.
- Turn a mesh (STL, OBJ, 3MF) back into STEP, IGES or BREP.
- Read native SolidWorks, Inventor or CATIA files. Export STEP or IGES from that program first.
| Extension | .3mf |
|---|---|
| Full name | 3D Manufacturing Format |
| Container | ZIP archive with XML data |
| Geometry type | Triangle mesh + metadata |
| Open standard | Yes (3MF Consortium) |
| Supports color | Yes — per-vertex, per-triangle, per-object |
| Supports materials | Yes — multiple materials per model |
| Supports assemblies | Yes — components and constellations |
What is a 3MF file?
3MF (3D Manufacturing Format) was developed by the 3MF Consortium (Microsoft, Autodesk, HP, Ultimaker, and others) in 2015 as a modern replacement for STL. A 3MF file is a ZIP archive containing XML geometry data plus optional color, material, texture, support structure, and print setting metadata. Unlike STL, 3MF supports full-color models, multi-material assemblies, per-triangle color, and structured metadata. File sizes are significantly smaller than ASCII STL. PrusaSlicer, Bambu Studio, Cura, and Chitubox all support 3MF natively.
Common Uses of 3MF Files
For multi-color or multi-material FDM printers (Bambu Lab AMS, Prusa MMU), 3MF carries per-part color and material assignments that STL cannot express.
HP Multi Jet Fusion and other powder-bed printers read full-colour and material data straight from 3MF.
3MF files can bundle slicer profiles and print settings, allowing print farms to reproduce exact configurations without manual re-configuration per job.
Software Support
PrusaSlicer, Bambu Studio, Cura, Chitubox, Windows 3D Builder, Autodesk Fusion 360, SolidWorks 2024+, and Materialise Magics.
Convert This Format
Commonly converted from STEP or STL for additive manufacturing, or to STL for compatibility with legacy slicers that do not yet support 3MF.
How to convert 3MF to STL
Add the .3mf files, pick STL and convert. Every object in the 3MF goes into the STL, in millimetres, at its place on the plate. Bambu Studio and PrusaSlicer project files both work.
cadconvert convert project.3mf -o project.stl cadconvert batch C:\prints\3mf -o C:\prints\stl -f stl
Measured with 3D CAD Converter 1.0.23 on a Ryzen 9 3900X: Bambu Studio's 9-object flow-rate plate gave a 6,920-triangle STL of 124 × 94 × 1.4 mm in 2.3 s. Step-by-step guide with real output
How to convert STL, OBJ or STEP to 3MF
3D CAD Converter turns STL meshes, OBJ models and STEP solids into print-ready 3MF files in three steps — one model or a whole folder at a time.
Add your source files
Drag an STL, OBJ or STEP file (or an entire folder) into 3D CAD Converter. Mixed formats in the same batch are fine.
Choose 3MF as the output
Select 3MF as the target format. For STEP solids, set the tessellation quality so curved surfaces are approximated as finely as you need.
Convert and open in your slicer
Run the conversion and open the resulting .3mf directly in PrusaSlicer, Bambu Studio, Cura or Windows 3D Builder — geometry, units and color travel inside one file.
Prefer the command line? The bundled cadconvert CLI converts to 3MF with a single command:
Convert a single STL mesh to 3MF cadconvert convert model.stl -o model.3mf Convert an OBJ model to 3MF cadconvert convert model.obj -o model.3mf Convert a STEP solid to 3MF cadconvert convert part.step -o part.3mf Batch-convert a whole folder to 3MF (recursive) cadconvert batch ./in -o ./out -f 3mf -r Treat source units as inches when writing the 3MF cadconvert convert model.stl -o model.3mf --units in
Add --quality 0.1 to control mesh fidelity when the source is a STEP solid. The 3MF file declares its unit, so the slicer opens it at the right size.
3MF vs STL — why 3MF is the modern choice
STL stores only raw triangles — no color, no materials, no units, no print settings. A 3MF file packs all of that into a single, compact, watertight ZIP-and-XML package: per-part color, multiple materials, embedded units (so a model is never mistaken for the wrong scale) and even slicer profiles. That is why Bambu Lab, Prusa and HP build their multi-color and production workflows around 3MF.
3MF is also smaller than ASCII STL and far less ambiguous: where STL leaves orientation and scale to guesswork, 3MF declares them explicitly, so the part that leaves your CAD tool is the part that prints. For single-color hobby prints STL is still perfectly fine, but for anything with color, multiple materials or shared print settings, 3MF is the better container.
Compare the alternatives in depth: STL, OBJ. Read STL vs OBJ vs 3MF for 3D printing.
STL, OBJ or 3MF: which format your print needs
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Common 3MF issues (and how to fix them)
Some legacy or device-bundled slicers predate 3MF support. If your slicer rejects a .3mf, convert it back to STL with 3D CAD Converter — geometry is preserved, you only lose color and metadata that the old slicer could not use anyway.
STL carries no color, so converting 3MF to STL and back drops every material assignment. Keep the original 3MF as your master and only export STL copies for tools that need them.
3MF embeds units, but a mesh built in inches and exported without unit info can import at the wrong size. Set --units in (or the equivalent in the desktop app) so the 3MF declares the correct scale.
PrusaSlicer, Bambu Studio, Cura, Fusion 360 and SolidWorks 2024+ read 3MF well, but some CAD viewers still do not. When in doubt, keep an STL or OBJ copy alongside the 3MF for maximum compatibility.
3MF — frequently asked questions
What is a .3mf file?
A .3mf file is a 3D Manufacturing Format model — an open standard from the 3MF Consortium. It is a ZIP archive holding XML geometry plus optional color, material, units and print-setting data in one watertight package, designed as a richer replacement for STL.
How do I open a 3MF file without a slicer?
On Windows, open it with the built-in 3D Builder or Paint 3D. You can also open it in Fusion 360 or SolidWorks 2024+, or convert it to STL or OBJ with 3D CAD Converter to view it in any mesh tool. Since a 3MF is a ZIP archive, you can even rename it to .zip and inspect the XML inside.
Is 3MF better than STL?
For modern 3D printing, yes. 3MF stores color, materials, units and print settings that STL cannot, in a single smaller, always-watertight file. STL remains handy for legacy slicers, but 3MF is recommended for multi-color, multi-material and print-farm workflows.
Can I convert STL to 3MF for free?
Yes. 3D CAD Converter offers a free trial that converts STL, OBJ and STEP to 3MF, including whole folders in batch. Run cadconvert convert model.stl -o model.3mf from the CLI, or use the desktop app and pick 3MF as the output.
Does 3MF keep colors when I convert from STL?
No. STL stores no colour, so STL to 3MF gives geometry only. The other way, 3MF to OBJ keeps one plain colour per object. Colours painted in Bambu Studio or PrusaSlicer and texture colours are not kept in any format.
Does a Bambu Studio project with several plates convert?
Yes, into one file. Every object in the project goes into the STL at its own position; the plates are not split into separate files. Filament and print settings stay in the 3MF.