How to Convert 3MF to STL: 4 Free Ways (No Upload Needed)
Convert 3MF to STL with a free in-browser converter, Bambu Studio, OrcaSlicer, PrusaSlicer, Cura or Blender, and what STL keeps from multi-object plates.
By Depthue Lab2 min read
3MF is the default project format in Bambu Studio, OrcaSlicer and PrusaSlicer, and more model sites publish it every month. STL is still what many older slicers, CAM programs and online services expect. Converting takes seconds once you know where the option lives.
Method 1: convert in your browser (fastest, private)
The converter below reads the 3MF on your own device, including multi-object plates, components and each object's position on the plate. Choose one merged STL or one STL per object, and download. Nothing is uploaded.
Method 2: Bambu Studio or OrcaSlicer
- Open the 3MF (drag it in, or File, Open project).
- Use File, Export and choose the STL option: all objects as one merged STL, or each object as its own STL.
- To export a single part, select it first, then right-click it and export it as STL.
- Reopen the STL to check scale and orientation.
Menu names shift a little between versions, but the export options sit under File, Export in both.
Method 3: PrusaSlicer or Cura
- PrusaSlicer: File, Export, Export plate as STL (or Export plate as STL including supports).
- Cura: open the 3MF, select the model, then File, Export, and choose STL as the file type.
Method 4: Blender
Blender imports 3MF with an add-on and exports STL natively. It is overkill for a simple conversion, but useful if you also need to repair or edit the mesh.
What you lose when you convert
| Kept in STL | Lost from the 3MF |
|---|---|
| Triangle geometry | Colors and multi-material assignments |
| Object shape and size | Print settings and profiles |
| Object positions (if merged) | Supports, modifiers and seams painted in the slicer |
| Units (STL has none; millimetres are assumed) |
If you convert a multicolor model, you get one STL per color part or one merged shape, with no color information. Keep the 3MF as your master copy.
Online converters and privacy
Upload-based converters work, but your file goes to someone else's server. That is fine for a downloaded model and a bad idea for a client's product, a paid design or anything unreleased. A local converter or your slicer does the same job without the upload.
After converting
Check the STL in a viewer before slicing. The free STL viewer shows dimensions in millimetres, triangle count and volume, which catches unit mistakes before they waste filament.
Free tools for this job
Frequently asked questions
What is the difference between 3MF and STL?
STL stores only a triangle mesh with no units, color or settings. 3MF is a zipped XML format that stores meshes in known units plus colors, materials, multiple objects, their positions on the plate and often slicer settings.
Can I convert 3MF to STL without installing anything?
Yes. The Depthue 3MF to STL converter runs in your browser and converts on your own device, so the file is never uploaded. It handles multi-object plates and build transforms.
Why is my converted STL the wrong size?
STL has no units, so the program that opens it has to assume one. 3MF records its unit, usually millimetres. Convert with a tool that reads that unit and keep your slicer set to millimetres.
Can I convert STL back to 3MF?
Yes. Import the STL into any modern slicer and save the project as 3MF. Colors and settings then have to be added again.
