STL vs OBJ
STL stores only triangles, which is all a 3D printer needs and why it has been the printing standard since 1987. OBJ adds colour, texture coordinates and materials. Print in STL. Anything visual, rendered or textured belongs in OBJ or glTF.
Side by side
| Spec | STL | OBJ |
|---|---|---|
| Type | 3D model | 3D model |
| Extensions | .stl | .obj |
| Introduced | 1987 | 1980s |
| Compression | None | None |
| MIME type | model/stl | model/obj |
| Use it when | Sending a model to a slicer or a 3D printer. | Moving static geometry between 3D applications that may not share a modern format. |
| Avoid it when | The model needs colour, textures or materials, or is destined for a web viewer or AR. Use GLB. | You need animation, or a single self-contained file. Use GLB. |
Where the usual answer breaks
Multi-material and colour printing. STL cannot express either, so those printers take 3MF or OBJ.
STL
- Accepted by essentially every slicer and 3D printer
- Dead simple format, hard to get wrong
- Decades of tooling support
- No colour, texture, material or animation data
- No units, so scale is ambiguous between applications
- Files get very large because vertices are repeated per triangle
OBJ
- Read by almost every 3D application
- Plain text, so it is inspectable and diffable
- Supports UV coordinates and per-face materials
- No animation or skeletal data
- Materials live in a separate MTL file that is easily lost
- Large and slow to parse compared with binary formats
Tools for these formats
STL to GLB Converter
Converts STL 3D models to GLB (glTF binary) entirely in your browser, no upload or account needed, ready for web viewers, Unity, or Godot.
STL to OBJ Converter
Converts STL mesh files to Wavefront OBJ format, useful when an older modeling tool or export pipeline expects OBJ instead of STL.
OBJ to GLB Converter
Turns Wavefront OBJ meshes into GLB (glTF binary), the format most web viewers, Unity, Godot, and AR tools expect by default.
Other comparisons
Last updated 2026-08-03