STL to 3MF Converter
Convert an STL to a 3MF package for 3D printing. STL has no colour, so the result is flat-coloured. Runs in your browser.
Drag & drop your STL file here
or click to browse
Supported Formats
Format Information
Source Format
STL.stl
STL (Stereolithography)
STL is an additive-manufacturing format from the 1990s: a flat list of triangles and nothing else. It has no concept of a scene, a material or a texture, which is why it is the lingua franca of 3D printing and also its most lossy interchange format.
What it carries: Triangle positions and, optionally, one facet normal per triangle. No UVs, no vertex colours, no materials, no node hierarchy, no animation.
Open a STL file in the viewerTarget Format
3MF.3mf
3MF (3D Manufacturing Format)
3MF is the modern replacement for STL, built for 3D printing and industrial additive manufacturing. It is an OPC package — a ZIP container holding XML metadata and mesh parts — which is why it can carry colour and material information that STL cannot.
What it carries: Triangle geometry, per-vertex colour and a base material colour. This converter writes geometry and colour; image textures and the wider 3MF material model are not written, and textures inside an imported 3MF are not read.
Open a 3MF file in the viewerAbout this conversion
STL's direct successor, and the format worth choosing if colour matters. The triangles are written into a 3MF package, which is a proper OPC container rather than a flat list.
Why convert STL to 3MF
- Get colour onto a print that STL cannot carry.
- Replace a bare STL in the print pipeline with a package that carries metadata.
- Store print assets in a container that can express a material model.
What happens during the conversion
Geometry
The triangle list is triangulated into an indexed mesh and written into the 3MF model part. The package is reloaded and validated before download.
Materials and textures
Colour is what 3MF adds over STL. An STL has no colour, so the mesh is written with the default colour the writer applies; you would need a colour-bearing source to get per-vertex colour through.
Common use cases
- Preparing a print file in the modern format slicers increasingly expect.
- Migrating an STL-only print workflow onto 3MF.
- Sharing a print asset in a container that can grow beyond geometry.
Limitations of this conversion
- No textures, normal maps or UVs are written.
- Normals are not written, so the slicer re-derives shading from the triangles.
- Since STL has no colour, the output will be a single flat colour rather than a coloured mesh.
- The 3MF that comes out declares its unit as millimetres. Your STL coordinates are passed through unscaled, so if you modelled in inches or centimetres, set the size in your slicer rather than trusting the label.
How to convert STL to 3MF
Three steps in the browser. Nothing is uploaded to a server, so an unwieldy file is limited only by your own device's memory.
Upload your .stl
Binary and ASCII STL are both supported. Normals are read, but the 3MF writer does not carry them into the package.
Convert to 3MF
The triangles are written into a validated 3MF package.
Preview in your slicer
Check the scale and orientation — STL carries no unit metadata.
Related tools and formats
Other conversions from this format
Check the file in a viewer
Frequently Asked Questions
Questions people ask when turning STL files into 3MF.
Looking for a different direction? See every supported conversion.