model → model
Convert OBJ to STL
Convert OBJ to STL in seconds. Free, no signup, no watermark, no file-size limit. Your file is processed in your browser and never uploaded.
At a glance
- Source
- OBJ
- Target
- STL
- Where it runs
- Your browser
- Cost
- Free, unlimited
- Account
- Not needed
Converter
OBJ to STL
Drop one or more wavefront mesh files.
or select wavefront mesh
Your file never leaves this browser
The details
What happens when you convert between 3D formats
A text-based 3D mesh format that has been around since the 1990s and refuses to die. The mesh is read, and its geometry, materials and animation are written out in the target format, converting units along the way. The result is a the mesh format for 3d printing. a list of triangles and nothing else, produced entirely inside your browser.
What survives
- The geometry, though often at a lower polygon count
- Materials and textures where the target format supports them
- The animation, where the target format supports it
What changes
- The polygon count, because many formats cannot hold a high-density mesh
- The material model, which differs between formats
Where it goes wrong
- Unit conversion is the classic trap — a model that was in centimetres can arrive in metres
- Materials written by a modern renderer may fall back to a plain colour in an older format
Why anyone would do this
The model has to live in a different tool, and the tool does not read the format you have.
About the format
A text-based 3D mesh format that has been around since the 1990s and refuses to die.
A plain text file listing vertices, texture coordinates, normals and the faces that join them, plus material references.
- Where it is good
- Readable — you can open it in a text editor and understand it
- Holds texture coordinates and material references
- Accepted by almost every mesh tool
- Where it falls short
- Very slow to load on big models
- The format has no official standard, so tools disagree on details
- No animation, no scene graph, no skinning
- You will find it on
- 3D software, renderers, academic datasets, older pipelines
The thing people miss
An OBJ of a moderately detailed object is usually several megabytes of text, because every triangle is written out longhand.
About the target
The mesh format for 3D printing.
Either an ASCII list of facets or a binary array of triangle records with normals and vertex coordinates.
- Almost every 3D printer and slicer reads it
- Very simple, so there is nothing to get wrong
- Fast to load into a slicer
Real jobs
What people are actually doing with OBJ
Moving a model between older and newer 3D programs
A scene a script needs to read and change
Archiving a mesh in a form that will still open
Specification
The details, in one table
| Source format | OBJ — Wavefront mesh |
|---|---|
| Target format | STL — STL mesh |
| Typical source size | 2–200 MB |
| Runs | In your browser |
| Account needed | No |
| Watermark | None |
| File extension | .obj → .stl |
How to
OBJ to STL, step by step
- 01
Add your wavefront mesh
Drag the file onto the drop zone, or tap to browse. Only one file is needed.
- 02
Choose the STL settings
Set the STL-specific options — everything happens locally, so the speed is your device, not a queue.
- 03
Download the result
The finished STL downloads to your device. Nothing is uploaded and nothing is retained.
Also available
OBJ converts into
Questions
OBJ conversion questions
What actually happens to my OBJ file when I convert it to STL?
The mesh is read, and its geometry, materials and animation are written out in the target format, converting units along the way. So the OBJ file is unpacked, the content is laid out, and the result is written out as STL. The geometry, though often at a lower polygon count survives unchanged.
Will converting OBJ to STL reduce the quality?
For this particular conversion, not in the way you would expect. The geometry, though often at a lower polygon count — the OBJ content is not re-encoded in a lossy way. The only thing that changes is the format it is stored in.
Is my OBJ file uploaded to a server?
No. This OBJ to STL conversion runs as JavaScript inside your browser tab. The file is read from your device and the result is written back to your device, so there is no upload step, no file-size limit and no copy of your OBJ file on any server.
Do I need an account or will there be a watermark?
Neither. There is no sign-up step, no email capture and no watermark on the output. The only limits are the ones your own device imposes.
What is the most common mistake people make when converting OBJ to STL?
Unit conversion is the classic trap — a model that was in centimetres can arrive in metres
Why would somebody convert OBJ to STL at all?
The model has to live in a different tool, and the tool does not read the format you have. In short: moving a model between older and newer 3d programs
Something most people do not know about OBJ?
An OBJ of a moderately detailed object is usually several megabytes of text, because every triangle is written out longhand.