GLB, glTF, OBJ, STL, FBX, PLY, 3MF, DAE, USDZ, ZIP · up to 250 MB · or drop it here
Pick an OBJ with its MTL and textures, or a glTF with its .bin, in one go. A ZIP that holds them works too.
Drop a 3D model to convert it. The file stays in this tab; nothing is uploaded.
3MF to STL converter
The 3MF to STL converter unpacks a 3MF in your browser and writes its triangles as a binary STL for any slicer. The unit the 3MF declares is applied, so the part keeps its real size in millimetres; colors, materials and print settings are left behind, and nothing is uploaded.
3MF to STL in numbers
A 3MF may declare micron, millimetre, centimetre, inch, foot or metre; the converter scales from that unit to millimetres.
The STL written is binary: an 80-byte header and a 4-byte triangle count come first, then 50 bytes for every triangle.
Choose 28, 50, 100 or 180 mm tall, or Original size to keep the dimensions the 3MF states.
The largest 3MF the page opens; the package is unzipped inside the browser tab.
What survives 3MF to STL
The geometry crosses; everything a slicer added around it stays in the 3MF.
| What | What happens |
|---|---|
| Every triangle in the buildKept | Each mesh the 3MF places on its build plate is written as triangles, with no decimation, smoothing or hole filling. |
| Real-world sizeKept | The unit named on the 3MF model element is applied, so a part modeled in inches arrives at the same physical size in millimetres. |
| Z-up orientationKept | Both formats stand parts on Z, so the STL lands on the bed in the pose the 3MF held. |
| Colors and painted filamentsDropped | Base materials, color groups and per-triangle filament paint have no place in an STL, so the file comes out one plain shape. |
| Plates and print settingsDropped | Supports, process settings and slicer metadata stay behind; only the meshes are written. |
Inside a 3MF
What a 3MF holds that an STL cannot
Why the same part needs a different file once it leaves the 3MF.
A package, not a mesh
A 3MF is a ZIP holding the model as XML, a content-types list, relationships and, when a slicer wrote it, that slicer's own settings files.
A unit written in
The model element says which unit its coordinates use. An STL has no unit field, so the converter writes millimetres, the unit slicers assume for STL.
Vertices listed once
In a 3MF triangles point into a shared vertex list. A binary STL repeats all three corners for every triangle and is not compressed, so the STL is usually the larger file.
Convert a 3MF to STL in three actions
STL is already selected as the output on this page.
Drop the 3MF
Pick or drop the .3mf file, up to 250 MB. The page reads the unit it declares and shows the part's size.
Keep the size or set a height
Leave Original size, or choose 28, 50, 100 or 180 mm to scale the part to that height.
Press Convert to STL
The binary .stl saves to your device, with the height in its file name when you chose one.
Limits of 3MF to STL conversion
An STL is the simplest print format, so some of the 3MF cannot come along.
A multicolor print loses its colors
A painted 3MF becomes one plain STL. For a multicolor print, keep the 3MF, or rebuild colors from a texture with the vertex-color tool.
Every object goes into one file
All meshes in the build are written to a single STL; cut it afterwards if the parts must print separately.
Faults are copied, not fixed
Open edges and inside-out faces in the 3MF reach the STL unchanged; run STL repair before slicing if the part is not a closed solid.
Questions about 3MF to STL
Answers about units, colors and slicer projects.