Convert STL to OBJ
Free · no signup · no watermark · runs in your browser · batch up to 20 files, download as ZIP
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STL and OBJ are both plain mesh formats, so this conversion keeps the geometry exactly. The usual reason to do it is that a modelling or rendering tool wants OBJ, or that you want to add UVs and materials later in a program that handles OBJ better than STL. The STL has no colour, so the OBJ gets a neutral grey material in its .mtl file.
This conversion runs entirely in your browser. The file is never uploaded, which makes it instant, private and usable on work files you would not want to send to a stranger's server.
It also works as a bulk STL to OBJ converter: drop up to 20 STL files at once, they are converted one after another in your browser, and you can download each file on its own or all of them together in a single ZIP. A file that fails is listed with the reason and does not stop the rest of the batch.
How to convert STL to OBJ
- Drop your STL files onto the box above, or click it to choose from your computer. Up to 20 at once.
- Check the 3D preview and model info. If the model is the wrong size or lying on its back, open the options to set the source units or rotate Z-up to Y-up, then press Convert.
- Download each converted file from the list, or press "Download all (.zip)" to get the whole batch in one ZIP file.
What changes when you convert STL to OBJ
OBJ keeps geometry, UVs, normals and basic materials (colour, roughness as shininess, opacity and the diffuse texture), written as an .obj with an .mtl and texture images in one ZIP. It has no animation or skinning.
STL and OBJ compared
| STL | OBJ | |
|---|---|---|
| Full name | Stereolithography | Wavefront OBJ |
| Extension | .stl | .obj |
| MIME type | model/stl | model/obj |
STL: The 3D printing workhorse: a list of triangles and nothing else. No colour, no materials, no UVs and no units (millimetres by convention), which is why every slicer and CAD tool can read it.
OBJ: Plain-text geometry with UVs and normals, read by nearly every 3D program. Materials live in a separate .mtl file and textures beside it; there is no animation and no unit.
Frequently asked questions
How do I convert STL to OBJ?
Drop your .stl file onto the box on this page and the .obj file is ready to download in a second or two. There is no signup, no email, no watermark and no file limit beyond what your browser can hold in memory.
Is this STL to OBJ converter free?
Yes, completely, with no account, no trial and no watermark on the output. There is nothing to buy on this page: choose a file, convert it and download the result.
Are my files uploaded anywhere?
No. This conversion runs entirely in your browser using JavaScript, so the file never leaves your computer. You can disconnect from the network after the page loads and it will still work.
Will converting to OBJ reduce the quality?
OBJ keeps geometry, UVs, normals and basic materials (colour, roughness as shininess, opacity and the diffuse texture), written as an .obj with an .mtl and texture images in one ZIP. It has no animation or skinning.
Can I convert multiple STL files to OBJ at once?
Yes, up to 20 files in one go. Drop or select them all together and they are converted one after another. Each file appears in the results list with its own download button, and "Download all (.zip)" saves the whole batch as a single ZIP. If one file cannot be converted, it is listed with the reason and the others still finish. For more than 20, run a second batch.
Found a problem, or something that could be better? We read every message and we fix things quickly.
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