3MF to STL Converter – Convert 3MF Files to STL Online
Upload a 3MF file and download a binary STL in your browser. Below the converter you will find what a 3MF actually contains, exactly what STL throws away, and how to do the same conversion in Bambu Studio, OrcaSlicer or PrusaSlicer.
Model files are processed in your browser and are not uploaded to a server.
STL keeps triangle geometry only. Colors, materials, textures, object names and slicer settings are not included. Import the STL in millimeters; it has no units field.
Your model preview will appear here after a valid file is converted.
Conversion runs locally in your browser. Nothing is uploaded to a server and no account is required for file conversion.
What you need to know before converting
Most people searching for 3MF to STL are trying to open a model in software that only accepts STL, or they downloaded a 3MF project from a model-sharing site. Both cases are really a format downgrade, so understanding the trade-off matters more than the button.
What is a 3MF file?
3MF (3D Manufacturing Format) is an open standard maintained by the 3MF Consortium. A .3mf file is a ZIP-based OPC package containing XML model definitions and related resources, rather than a raw list of triangles.
Because it is a container, 3MF can carry color and material assignments, multiple named objects and component instances with transforms, explicit millimeter units, textures, thumbnails, and slicer or printer settings. Bambu Studio, OrcaSlicer and PrusaSlicer save their projects as 3MF, which is why models downloaded from MakerWorld or Printables often arrive in this format.
STL, by contrast, was designed in the late 1980s for stereolithography and stores nothing but triangle geometry. Converting 3MF to STL is therefore not a repair or an upgrade: it is a deliberate reduction to the lowest common denominator that older tools, CAM software and some online services can read.
What you lose when converting 3MF to STL
STL keeps vertex positions, triangles, and the placement of the model in space. Everything that made the 3MF a manufacturing document is dropped. Be clear about this before you overwrite your only copy of a project.
Colors and material assignments, including Bambu AMS filament slot mapping.
Layer and multi-part structure: separate objects, component instances and their transforms are flattened into one triangle mesh.
Textures, object names, build plate layout, thumbnails and metadata.
Slicer settings, print profiles, supports and printer presets.
Unit declaration: STL has no units field, so the importer decides what the numbers mean.
Anything that cannot be recovered by converting the STL back to 3MF later.
How to convert 3MF to STL, and which software to use
There are three practical routes. They all produce roughly the same geometry-only STL; the difference is whether you already have the file open in a desktop application and whether you need to edit the model first.
Browser converter (this page): drop in a .3mf, check the triangle count, part count and millimeter dimensions in the preview, then download a binary STL. Best for a one-off conversion with nothing to install and no file upload.
Desktop slicers: open the 3MF project in Bambu Studio, OrcaSlicer or PrusaSlicer and use their export-as-STL option to save the plate or the selected model. Menu names differ between versions. Colors and print settings are still discarded, but this is convenient when the project is already tuned in that slicer.
CAD and mesh editors: Blender, Fusion 360, FreeCAD and similar tools can export STL after importing the geometry. Some need a 3MF plugin or an intermediate format. Use this route when you also need to repair, cut or remodel the mesh.
If a model from a sharing site already ships an STL, use that file directly. Re-converting adds no detail and still loses the color information.
Using the exported STL in Bambu Studio or PrusaSlicer
Import the STL using millimeters. STL does not declare units, so an importer that assumes inches will scale the model by 25.4 and produce a part that is wildly oversized or tiny. Check the reported dimensions against the preview shown before download.
If the original 3MF was a multicolor print, you will need to reassign colors in the slicer by painting, by height range, or by splitting the mesh into separate parts. That artwork does not survive the conversion, and a 3MF written back from the STL will not recreate it.
The converter does not remesh, repair holes or reconstruct missing surfaces. Mesh-based core 3MF assemblies and Production Extension component references are supported; G-code-only archives, slice-only models and unknown required extensions are rejected with an explanation. Print settings have to be configured again in your slicer.
3MF vs STL: what survives the conversion
A side-by-side view of what each format can store. This is why a 3MF to STL conversion is lossy in one direction only.
Property
3MF
STL
Triangle geometry
Yes
Yes
Declared units (millimeters)
Yes
No — importer decides
Colors and materials
Yes
No
Multiple named objects
Yes
Flattened into one mesh
Component transforms
Yes
Baked into triangles
Textures and thumbnails
Yes
No
Slicer and printer settings
Yes
No
File structure
ZIP / OPC package with XML
Binary or ASCII triangles
Based on core mesh-based 3MF and standard STL. Slicer-specific extensions vary by application and version.
Frequently asked questions
How do I convert a 3MF file to STL?
Upload the .3mf file to the converter above, review the geometry preview, then download the binary STL. Alternatively, open the 3MF project in a desktop slicer such as Bambu Studio, OrcaSlicer or PrusaSlicer and export the model or plate as STL. Both routes discard colors and print settings.
What software can open 3MF and export STL?
Bambu Studio, OrcaSlicer and PrusaSlicer all open 3MF projects and offer an STL export. Mesh editors such as Blender can export STL after a 3MF import, sometimes via a plugin. For a single file without installing anything, a browser-based converter is the quickest option.
Does converting 3MF to STL lose colors and layers?
Yes. STL stores only triangles. Colors, AMS filament assignments, layered or multi-part structure, textures and slicer settings are removed, and separate objects are merged into a single mesh. Keep the original 3MF if you need any of that information.
Can I convert a Bambu Studio or PrusaSlicer 3MF project to STL?
Mesh-based core 3MF files with printable build items and Production Extension component references are supported. G-code-only archives, slice-only models and files requiring unknown extensions are not converted. Printer presets and filament assignments are never transferred into the STL.
Why is my converted STL the wrong size in my slicer?
STL has no units field. Our converter interprets 3MF geometry in millimeters, so import the STL as millimeters too. If your slicer assumes inches, the model will appear 25.4 times larger than intended.
Is the 3MF to STL converter free, and are my files uploaded?
File conversion runs entirely in your browser with no account and no server upload. Image-to-3MF generation is a separate service with its own plan limits, but 3MF/STL file conversion is local.
Can I keep separate parts when converting 3MF to STL?
A single STL is one triangle mesh. If you need distinct parts, export them separately from the source application or keep the 3MF. Converting back from STL will not rebuild the original part structure or colors.
How do you convert 3MF to STL, and what information is lost?
Open the 3MF in a converter or slicer and export it as STL. The STL keeps only triangle geometry and the model placement interpreted in millimeters. It discards colors, materials, AMS filament assignments, multi-part structure, textures, object names and slicer settings. Import the result as millimeters, then reassign colors and print settings in your slicer.
Drop a .3mf file into the converter above, check the preview dimensions, and download the STL. Keep the original 3MF if you still need its colors and print settings.