Converters · OBJ → STL
OBJ to STL Converter
Free, private, in your browser. Convert OBJ to STL — no signup, no upload.
Unlike online converters that upload to a server, your file never leaves your browser.
⇄ Need STL to OBJ instead?Drop your 3D file here
or click to browse — .obj files up to 200 MB
When to convert OBJ to STL
You modeled or downloaded an OBJ and need a printable STL for your slicer — the single most common reason people leave OBJ behind.
OBJ vs STL: what’s the difference?
OBJ is the plain-text mesh format used across Blender, Maya and countless CAD tools, storing geometry with UV coordinates and named vertices, plus an optional .mtl sidecar for materials. STL is the 1987 universal standard: a bare triangle list with no color, units or UV that every slicer and printer accepts. Converting OBJ to STL reduces the model to the pure geometry a slicer needs, discarding the material and UV data a 3D printer never uses anyway.
What OBJ → STL keeps and drops
Preserved
- ✓Every triangle of the geometry, exactly
- ✓Real-world scale and dimensions
- ✓Model orientation
Dropped
- ✗Materials from the .mtl file — STL cannot store color or materials
- ✗UV coordinates — STL has no texture channel
- ✗Named vertex and face groups, flattened to raw triangles
How to convert OBJ to STL
- 1Drop your .obj file onto the box above, or click to browse.
- 2The file is parsed in your browser — nothing is uploaded.
- 3Check the 3D preview, then click “Convert to STL”.
- 4A binary STL downloads, ready to import into any slicer.
STL carries only geometry, so any .mtl materials and UVs are left behind — this is expected for 3D printing. Check that your mesh is watertight (no holes or non-manifold edges) before slicing; OBJ files from sculpting tools are not always solid, so run our free STL Repair if the print looks broken.
OBJ to STL — FAQ
What happens to the .mtl material file?
It’s not used — STL can’t represent materials, so only the geometry from the .obj is converted.
Is the output watertight?
The converter preserves your source topology as-is. If your OBJ has holes or non-manifold edges, run it through our free STL Repair tool first.