How to convert 3MF to STL
- Drop your
.3mffile into the box above, or click Choose file. - Check the objects you want. Multi-plate projects get a Plate menu, so you can export just one plate.
- Keep STL selected and click Download STL. Tick One file per object to get a ZIP with a separate STL for every object.
Conversion runs in your browser with JavaScript. A project with a few hundred thousand triangles converts in about a second on a typical laptop.
What the converter understands
- Bambu Studio, OrcaSlicer and MakerWorld projects — objects split into separate files, plates, part names and filament colours.
- PrusaSlicer projects — objects with several volumes and per-volume extruder colours.
- Any standard 3MF — Cura, Fusion, Windows 3D Builder, Microsoft samples: build transforms, components, units and material colours.
- Modifier, negative, support blocker and enforcer volumes are recognised and left out of the export, so you don't get stray boxes in your STL.
Why a 3MF can turn into a messy STL elsewhere
A slicer project is more than a mesh. Bambu Studio and OrcaSlicer store each object's parts in separate files inside the archive, keep modifier boxes for local settings, and spread objects across several plates. Converters that only read the main model file either miss those parts or merge everything into one lump, including the modifier boxes.
This tool rebuilds the project the way the slicer sees it, then writes only the printable parts. Each object keeps its position, or is centred on the bed if you leave Center on the bed on.
What you lose with STL
STL stores triangles and nothing else: no colours, filament assignments, part names, print settings or units (millimetres are assumed). If you need to keep colours or separate parts, export OBJ or a standard 3MF instead.
Frequently asked questions
Is this 3MF to STL converter free?
Yes. There is no sign-up, watermark or file size limit beyond what your browser's memory can hold.
Are my files uploaded?
No. The 3MF is read and converted inside your browser tab. You can disconnect from the internet after the page has loaded and the converter keeps working.
Can I convert a MakerWorld 3MF to STL?
Yes. MakerWorld downloads are Bambu Studio project files. Open the file here, pick a plate or objects, and download STL.
How do I export each object as a separate STL?
Select the objects, tick One file per object (ZIP) and download. Each STL is centred on its own, ready to arrange in another slicer.
Why are some boxes missing from my export?
Modifier volumes, negative volumes and support blockers or enforcers are not printed geometry, so they are left out. Tick Include modifier and negative volumes if you really want them in the file.
Are colours or multi-material painting kept in STL?
No — STL has no colour information. Part and filament colours are kept in OBJ, GLB and 3MF exports. Colour painted with a slicer's paint brush tool is not converted yet.