Free online 3MF to STL converter

3MF is the default project format in Bambu Studio, OrcaSlicer, and PrusaSlicer, and most models on MakerWorld and Printables download as a 3MF. It is a zipped package that holds the meshes plus the plate layout, units, colors, and print settings. STL holds one thing: a list of triangles. You need that simpler file when a CAD or modeling program, a resin slicer, a print service, or an older workflow only accepts STL, or when you want to edit a single part without the rest of the project. A 3MF to STL converter unpacks the project, reads each object, and writes out plain geometry that every slicer and 3D tool can open.

Choose one STL when you want the whole plate as a single file, for example to print it again in another slicer or to send it to a print service. Every object stays where it sat on the plate, so the layout is kept. Choose STL per object when you want to edit, scale, or recolor parts separately: you get a ZIP with one STL for each object, named after the object in your slicer. Parts inside one object, such as a body and a lid you split in Bambu Studio, are saved together in that object's STL. Most slicers center a model on import, so the plate position of a single-object STL rarely matters.

STL has no place for anything except triangles, so painted colors, filament and AMS assignments, per-object print settings, supports you painted, and the slicer project itself stay in the original 3MF. Modifier volumes, negative parts, and support blockers are left out rather than turned into solid geometry, which is what a basic converter would do; a cut-out that depended on a negative part is not applied. Units are handled for you: a 3MF saved in inches, centimeters, or meters is converted, so the STL is always in millimeters, the unit slicers assume. Keep the original 3MF if you may need the colors or settings again.

A project 3MF from Bambu Studio or OrcaSlicer converts directly, including files with several plates: all objects are read, and STL per object is the easy way to take them apart. A .gcode.3mf is different. It is a sliced print job made for the printer, and it may not contain the model mesh at all. If the converter reports that no mesh was found, download the project 3MF or the STL from the model page instead. You can also export an STL inside Bambu Studio by right-clicking the object and choosing Export as one STL, but this converter works the same on any computer and needs no slicer installed.

Converting 3MF to STL changes the file format, not the mesh. If an object had holes, flipped faces, or non-manifold edges in the 3MF, the STL has them too. Your slicer usually tells you when it finds errors. For a single STL, run it through the STL repair tool. If you would rather keep every object separate and in 3MF, use 3MF repair on the original file first, then convert.