STL to 3MF converter: the surface, as it is
Drop an .stl and get one .3mf file, converted in Blender on our server. The trip keeps the geometry and nothing more; nothing the source holds is lost on the way. Free, no account, nothing to install.
How do I convert STL to 3MF?
Drop the file on this page, wait while the server converts it, and download one .3mf file.
- 1Choose an .stl. Files up to 50 MB.
- 2The converter opens it in Blender on our server and writes 3MF. Most files take under a minute; the page shows the result in 3D when it is done.
- 3Download one .3mf file. The upload and the result are deleted 3 days later.
- In:
- .stl, ASCII or binary
- Out:
- one .3mf file
- Keeps:
- the geometry
- Cost:
- free, no account
What survives the trip
An STL is a list of triangles and nothing else, ASCII or binary. There are no materials, no texture coordinates, no colours and no unit: the numbers are taken as they are. The Z-up of printing is turned so the part stands upright in Y-up formats.
The result is one .3mf with every mesh as a separate part, a material per part carrying the base colour of the source, and the unit set to millimetres. Bones, skin weights, shape keys and animation do not exist in 3MF and are not written. An STL on the way in is taken as millimetres, so a 100-unit STL becomes a 100 mm part.
STL and 3MF do not hold the same things, and the page says so before you upload: the trip keeps the geometry and nothing more, and nothing the source holds is lost on the way. 3MF is what Bambu Studio, PrusaSlicer, Cura, Orca and the Windows 3D Viewer open directly.
What this conversion cannot do
Measured on real files, not assumed. Everything below is a property of the formats or of the pipeline, and knowing it beforehand is cheaper than discovering it in your 3D tool.
Every unit is taken as a millimetre
STL has no unit field, and 3MF needs one, so each unit of the STL becomes a millimetre: a part modelled in millimetres arrives at its size, a part modelled in inches arrives 25.4 times too small. Scale it in the slicer if so.
One colour per part
A 3MF gives each part a material with a base colour. The source carries no colour, so every part gets a plain default colour and the filaments are chosen in the slicer.
Uploads stop at 50 MB
A larger file is refused before anything is uploaded. Decimate a dense mesh or shrink the textures in your 3D tool first; neither changes the format.
Frequently asked questions
ASCII or binary STL?
Both are read. They hold the same triangles; the ASCII form is several times larger, so it reaches the upload limit with far fewer triangles.
Which slicer opens the result?
Any that reads 3MF: Bambu Studio, PrusaSlicer, OrcaSlicer, Cura, and the Windows 3D Viewer. The file states millimetres, so the part arrives at the size it was modelled when the source stated its unit.
Is anything uploaded, and for how long?
Yes: the file you drop goes to our server in New York, is converted there, and both the upload and the result are deleted 3 days after the conversion. Nothing is shared with anyone.
Can I look at the STL first?
Yes, without uploading anything: the STL viewer draws it in your browser. Open the STL viewer →
Can this become a VTuber avatar?
Not as it is: an avatar needs a skeleton, skin weights and a face that moves, and an .stl has none of them. Rig and texture the model in Blender first, then convert the rigged file to VRM.
The other format pairs
All 50 are free, all run the same pipeline, and all say what they drop.
STL to GLB
STL in, GLB out, free: one file.
STL to FBX
STL in, FBX out, free: one file.
STL to OBJ
STL in, OBJ out, free: zipped with its files.
STL to PLY
STL in, PLY out, free: one file.
STL to DAE
STL in, DAE out, free: zipped with its files.
STL to USDZ
STL in, USDZ out, free: one file.
3MF to GLB
3MF in, GLB out, free: one file.
GLB to 3MF
GLB in, 3MF out, free: one file.
3MF to FBX
3MF in, FBX out, free: one file.
FBX to 3MF
FBX in, 3MF out, free: one file.
3MF to OBJ
3MF in, OBJ out, free: zipped with its files.
OBJ to 3MF
OBJ in, 3MF out, free: one file.
3MF to STL
3MF in, STL out, free: one file.
GLB to STL
GLB in, STL out, free: one file.
FBX to STL
FBX in, STL out, free: one file.
OBJ to STL
OBJ in, STL out, free: one file.
PLY to STL
PLY in, STL out, free: one file.
DAE to STL
DAE in, STL out, free: one file.
USDZ to STL
USDZ in, STL out, free: one file.
Only want to look at the file? GLB viewer, FBX viewer and OBJ viewer all run on your own device — nothing is uploaded.
Is your model going into VTubing?
An .stl is a surface without a skeleton, so no converter can make a VRM avatar out of it directly. Rigged and textured in Blender, the same model converts to VRM on the FBX to VRM converter, with the bones mapped onto the VRM humanoid.
Open the VRM converter