Converter pages
Which STL converter to pick
Start from the program that will open the file next, not from the file you have. A slicer wants a mesh, so the target is STL or 3MF. Pick 3MF when the receiving tool reads it, because the file records millimetres and nobody has to guess the scale. Pick STL when you do not know what the other side runs. Binary STL is the default here, and ASCII is there for tools that ask for text.
A web page, a game engine or a scene editor usually wants GLB or glTF, while OBJ suits modelling programs and older pipelines. STEP goes to CAD, and that direction has its own section below. If your pair has a page in the table, use it: the page filters the file picker to your format and converts as soon as the file is in.
Which conversions work
The converter reads 16 tested file types and writes 10 targets. Read across: the first column is the file you have, the rest is what you can save.
| From \ to | STL | 3MF | OBJ | GLB / glTF | STEP |
|---|---|---|---|---|---|
| STEP / IGES | yes | yes | yes | yes | faceted |
| STL | ASCII ↔ binary | yes | yes | yes | faceted |
| 3MF | yes | re-save in mm | yes | yes | faceted |
| OBJ | yes | yes | re-save | yes | faceted |
| GLB / glTF | yes | yes | yes | GLB ↔ glTF | faceted |
| FBX 7.x | yes | yes | yes | yes | faceted |
| PLY | yes | yes | yes | yes | faceted |
G-code is the odd one: G-code to STL rebuilds the printed shape from the extrusion lines, and the STL to G-code slicer goes the other way.
How every target was checked
Each of the 10 targets was written from a 20 mm test cube and opened again: same size, same volume, same triangle count. The heavier pairs were repeated on a 9,024-triangle sphere, including STEP → STL, IGES → STL, 3MF → STL, STL → STEP and STL → 3MF. GLB conversions were run on a Draco-compressed model exported by Blender with 21,696 triangles.
A converted file is a new download. The original on your disk is never touched.
What every converter page does the same way
The file is read and written in this tab. In the full test run every request went to the site's own origin and nothing was posted, so a supplier part under NDA stays on your machine. After the conversion the model stays in the viewer, and a bar shows the file name and size with Download, Other formats and Convert another file.
Before you download, look at the Info panel. Width, depth and height should match what you expect in millimetres. If a part reads 25.4 times too small, it was drawn in inches, and Edit → Size → Inches → mm fixes it before you save. You can repeat our own re-open check in a few seconds: drop the download back on the page and compare size, volume and triangle count.
Settings that change the result
- Tessellation for STEP and IGES input: Coarse for a smaller file, Fine for smoother curves.
- Rotate Y-up model to Z-up for OBJ, glTF and FBX models heading to a slicer, so the part does not lie on its side.
- STL ASCII or binary: binary is the compact default; ASCII is readable text for tools that ask for it.
- glTF as one file or as .gltf + .bin in a zip; both open again with the same geometry.
Units follow the source. STEP, IGES and DAE declare a unit and are converted to millimetres, and 3MF is written in millimetres. STL, OBJ and PLY carry plain numbers, which the viewer treats as millimetres. GLB keeps its raw numbers too, but glTF viewers read them as metres, so a 20 mm part can show up as 20 m in another program.
Mesh to CAD is the direction that needs care
Every pair that ends in a mesh is a plain translation, triangles in and triangles out. Going from STL, OBJ, 3MF or GLB to STEP works differently. The converter writes a faceted body in which each triangle becomes a flat face, and the faces form a closed shell that re-opens in OpenCascade with the same triangles. At about 1 KB per triangle, a dense scan makes a very large STEP, so reduce the triangle count first when the CAD side only needs the outline.
A faceted STEP has no true cylinders, holes or fillets that CAD can pick as features. It serves as a reference body for fitting a bracket or checking clearances. We have not yet opened these files by hand in desktop CAD programs, so try one in yours before you send it on. If the part needs real features, rebuild it in your CAD program on top of the faceted STEP.
Where the converter stops
It converts one file at a time; batch conversion is not part of this version. It cannot write FBX, DAE, 3DS, WRL, AMF or USDZ, so a scene that has to leave as FBX goes out as GLB or OBJ instead. FBX 6.x files do not open at all. The viewer names the version and asks you to re-export as FBX 2014/2020, OBJ or glTF from the program that made the file.
Questions and answers
How do I convert a file to STL?
Open the file here, press Convert and choose STL. Each pair page, such as STEP to STL, converts as soon as the file opens and shows one Download button.
Is the 3D model converter accurate?
On the test files every target re-opened with the same size, volume and triangle count. CAD input is approximated by triangles; Fine tessellation keeps curves closest.
Can I convert to FBX?
No. There is no FBX writer. FBX files can be read (version 7.0 and newer) and saved as OBJ, STL, GLB or glTF.
Do converted files keep colours?
STL holds no colour, so converting to STL drops it. 3MF, OBJ and GLB can carry it; texture handling has not been tested on our side yet.
Are my files uploaded for conversion?
No. Conversion runs in this tab. The test run recorded zero requests to other domains and nothing posted.