Convert OBJ to STL
Convert a Wavefront OBJ into an STL ready for slicing and 3D printing.
Free, no account, up to 50 MB per file. Uploads are private and deleted after 24 hours unless you sign in, which claims them and keeps them for 7 days.
What survives OBJ → STL
- Geometry
- Triangle winding
What is not carried across
- Materials and textures — the target format cannot store them.
- UV coordinates.
- Object names and scene hierarchy.
About Wavefront OBJ files
- An OBJ stores geometry only. Its materials live in a separate .mtl file, and its textures in separate image files.
- Uploading the .obj on its own converts the geometry. The materials and textures are not part of that file, so they cannot be carried across.
- Vertex colours written by some scanners are read where present.
Why STL
- The format every slicer and 3D printer toolchain accepts.
- Nothing but triangles, so there is nothing to go wrong on import.
Common problems
- The printed model is the wrong size.
- Neither OBJ nor STL declares units. The numbers are unchanged by the conversion, so set the scale in your slicer.
- The slicer reports a non-manifold mesh.
- That is a property of the source geometry, not of the conversion. Repair it before converting.
After converting
Converting changes the container, not the geometry — a heavy model stays heavy. If the result is destined for the web or a game engine, reducing its triangle count is the part that makes it load faster.