Compare
STL vs OBJ
STL is common for sending triangle meshes to 3D printing; OBJ can carry mesh attributes and may reference materials separately.
Which format should you choose?
Use STL when the slicer asks for it; consider OBJ when the workflow supports its additional mesh attributes.
Good fit for STL
3D printing
- Passing a printable surface model from CAD to a slicer
Good fit for OBJ
Mesh exchange
- Moving a static mesh between 3D modeling applications
Basic information
| Field | STL | OBJ |
|---|---|---|
| Extension | .stl | .obj |
| MIME type | model/stl | model/obj |
| Common uses | 3D printing | Mesh exchange |
| How to open | Open in a 3D viewer or slicer and verify dimensions and mesh integrity. | Open in an OBJ-capable viewer or 3D editor and check MTL and texture references. |
| Export or convert | When converting from OBJ or FBX, verify retained detail, units, scale, and triangle orientation. | When converting, inspect face orientation, materials, textures, units, and scale. |
Choose by use case
Passing a printable surface model from CAD to a slicer
3D printing
STLMoving a static mesh between 3D modeling applications
Mesh exchange
OBJKey point 1
STL focuses on triangulated surface geometry.
More on the differencesKey point 2
OBJ can include normals and texture coordinates and may use a companion MTL file.
More on the differencesMore on the differences
Check units, scale, normals, and watertightness in the target slicer. Keep companion files together when needed.
- STL units are often agreed outside the file.
- OBJ can describe material references, but support depends on the application.
Frequently asked questions
Which format is better for 3D printing?
Use the format supported by your slicer. STL is common for simple printable meshes; verify dimensions and mesh integrity after import.
Can STL preserve OBJ materials and textures?
Usually not as a standard STL workflow; use a format and slicer that support the required appearance data.