How to convert 3MF to STL
- Drop your .3mf file into the box above, or click Choose file.
- Check the 3D preview, size and triangle count.
- Make sure STL is selected as the output format. Adjust scale or up-axis if needed.
- Click Download. The .stl file is created instantly on your device.
Why convert 3MF to STL?
Some older slicers, CAM tools and online print services still only accept STL. Converting 3MF to STL keeps every object's geometry in millimetres; colours, materials and slicer settings are not part of STL and are dropped.
What changes in the conversion
- Colours are dropped. STL only stores geometry.
- Geometry is preserved. Every triangle, with all object transforms applied, ends up in the new file.
3MF vs STL
| 3MF | STL | |
|---|---|---|
| Full name | 3D Manufacturing Format | Stereolithography |
| Stores | geometry, units, colours and (slicer-specific) print settings | geometry only |
| Colour | Yes | No |
| Textures | No | No |
| Units | stored in the file (usually millimetres) | none – most programs read STL numbers as millimetres |
| Exact CAD geometry | No | No |
About the formats
3MF (3D Manufacturing Format) was developed by the 3MF Consortium (Microsoft, HP, Autodesk, Ultimaker and others) since 2015. It is a zipped XML package that stores meshes together with units, colours, materials and print settings. It is the modern replacement for STL in 3D printing – PrusaSlicer, Bambu Studio and Cura save projects as 3MF.
STL (Stereolithography) was created by 3D Systems in 1987 for its stereolithography printers. It describes only the surface of a model as a list of triangles, without colour, materials or units. It is the default file for 3D printing and the format almost every slicer (Cura, PrusaSlicer, Bambu Studio, Chitubox) opens.
Frequently asked questions
Is this converter free?
Yes. You can convert 3MF to STL for free – up to 3 conversions a day, with no sign-up and no watermark. If you need more, Pro gives you unlimited conversions and batch conversion (free for 7 days).
Are my files uploaded to a server?
No. The conversion runs entirely in your browser using WebAssembly and JavaScript. Your model never leaves your computer, which also makes it safe for confidential parts and patient data.
Is there a file size limit?
There is no fixed limit. Files of a few hundred megabytes work on a typical laptop; the practical limit is your device's memory.
Are my print settings kept?
No. Slicer settings (layer height, supports, filament profiles) are stored in vendor-specific parts of the 3MF that STL cannot represent. Only the geometry is converted.
My 3MF came from Bambu Studio or PrusaSlicer – will it work?
Yes. Project files from Bambu Studio, OrcaSlicer, PrusaSlicer and Cura are standard 3MF packages; the meshes inside are read and placed exactly as on the build plate.