OBJ to STL Converter
Convert a Wavefront OBJ model to STL - the universal format every 3D printer and slicer understands.
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About Converting OBJ to STL
OBJ is a widely supported 3D geometry format that stores vertices, faces, texture coordinates and normals as plain text. It is a common interchange format between modelling, rendering and CAD applications, optionally pairing with an .mtl file for materials. When you need to move away from OBJ, the usual reason is simple: materials live in a separate .mtl file.
Converting your OBJ 3D model to STL solves that. STL is the universal 3D-printing format. It describes a model as a raw triangle mesh — just the surface geometry, with no colour, texture or units. Nearly every slicer and 3D printer accepts it, which is why it is the default export from most CAD tools for printing. In practice you gain understood by virtually every 3d printer and slicer and simple, robust triangle mesh. PrivConvert runs the whole OBJ-to-STL conversion in server memory and deletes your file the instant the STL is ready — nothing is stored, logged or reused.
When this conversion helps
- You need understood by virtually every 3D printer and slicer
- You need simple, robust triangle mesh
- You need compact for a plain surface model
- Sharing a OBJ 3D model with someone whose software expects STL
Tips for best results
- Files up to 250 MB are supported, and you can batch-convert several OBJ files at once; each is processed privately and deleted immediately.
How to Convert OBJ to STL Online
You can convert OBJ to STL right in your browser in under a minute. What you gain with STL: understood by virtually every 3D printer and slicer.
Drag and drop your file into the upload area, click to browse your device, or paste a URL to a file hosted online. You can upload files up to 250 MB and batch convert up to 20 files at once.
Once uploaded, the conversion from OBJ to STL starts automatically. The process runs entirely in an isolated environment - your data never leaves the secure pipeline.
Your converted file is ready instantly. Click the download button to save it to your device. The file is deleted from memory immediately after download.
A more private way to convert OBJ files
Plenty of sites convert OBJ files. Very few promise never to keep them — PrivConvert does, and backs it up with how the service is built.
Files are processed in volatile memory (RAM) and purged the instant your download is ready — nothing is ever written to disk, cached or backed up.
Every upload and download is protected with TLS 1.3, so your 3D model cannot be intercepted on the way to the server or back to you.
Convert instantly with no sign-up, no email and no profiling cookies. We never build a profile around you or the files you convert.
Runs in any modern browser on Windows, macOS, Linux, Android and iOS — no install, plugin or desktop software needed.
OBJ vs STL - Format Comparison
| Feature | OBJ | STL |
|---|---|---|
| File extension | .obj | .stl |
| Full name | Wavefront OBJ | Stereolithography |
| Introduced | 1990 | 1987 |
| Encoding | Text | Binary |
| Editable | No | No |
| Open standard | Yes | Yes |
| Supported by PrivConvert | Yes (as input) | Yes (as output) |
| Privacy-safe conversion | In-memory, zero storage | |
| Max file size | 250 MB per file | |
| Batch support | Up to 20 files simultaneously | |
A converter you do not have to worry about
PrivConvert handles thousands of conversions every day for developers, designers and privacy-conscious people who need a 3D model converted without handing over a permanent copy.