Convert 3MF to STL
Drop a 3MF file below and get an STL back. The whole conversion runs in your browser, so your file never gets uploaded to a server, never leaves your machine, and nothing is stored.
STL is the format most slicers and older printers expect. 3MF carries more than STL can hold, so this conversion simplifies the model down to plain geometry. The "Honest note" further down spells out exactly what changes.
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How it works
Good to know
FAQ
What exactly do I lose going from 3MF to STL?
Two things. Color and material data are dropped, because STL has no place to store them. And if your 3MF holds several separate objects, they get merged into one continuous mesh, since STL has no concept of distinct parts. The shape and surface detail of the geometry itself are preserved.
Will the size and scale stay correct?
Yes, in nearly all cases. 3MF records explicit units (usually millimeters), and we carry the geometry across at that scale, so a 50 mm part stays 50 mm. STL itself stores no units, so your slicer assumes millimeters on import. If yours defaults to inches, set it to millimeters and the part will measure correctly.
I have multiple objects on one plate. Can I keep them separate?
Not in an STL. STL is a single triangle soup with no part boundaries, so everything in the 3MF comes out as one merged mesh. If you need the objects to stay separate, keep them in 3MF, or split them in your slicer or modeling tool before exporting. Most slicers can still auto-separate disconnected shells after import, but touching or overlapping parts will fuse.
Is the STL still good for 3D printing?
Yes. STL is the most widely accepted print format, and the geometry comes through intact, so it slices and prints fine. You'll just set color, supports, and per-object settings in your slicer instead of inheriting them from the 3MF. For multi-color or multi-material prints, it's usually better to keep the 3MF.
How big a file can I convert, and is it really private?
It runs on your own machine, so the practical limit is your device's memory, not an upload cap. Large, high-triangle 3MF files use more RAM and take a few seconds longer. On privacy: the conversion is 100% in-browser. The file is never sent anywhere, and we keep no copy because we never receive one.