Preserved
- Supported surface geometry is preserved.
Polygon mesh conversion for 3D printing
OBJ to STL Converter Online
Turn Wavefront OBJ mesh files into slicer-ready STL output without installing desktop software. Objects are processed locally, and separate OBJ meshes remain separate STL parts.
Drop OBJ file here
or browse your computer
Max 100 MB · processed locally
Your model stays on this device. Parsing, conversion, verification, and download preparation run locally in this browser.
What the conversion keeps and removes
Converted
- Quads and polygons are triangulated.
- Object placement is baked into output coordinates.
- Normals become per-facet STL normals.
Lost
- OBJ object and group hierarchy is lost.
- UV coordinates are lost.
- Vertex colors are lost.
- MTL materials are lost.
- Texture images are lost.
Unsupported input
- OBJ and STL are unitless; confirm the intended unit.
- Confirm the source orientation before conversion.
- Cameras and lights cannot be reconstructed.
- Animation cannot be reconstructed.
- Exact CAD surfaces cannot be reconstructed.
- Manufacturing metadata cannot be reconstructed.
- Print settings cannot be reconstructed.
When OBJ to STL makes sense
Convert OBJ to STL when a polygon model from Blender, Maya, a model marketplace, photogrammetry software, or a CAD mesh export must enter a geometry-only 3D-printing workflow. Vertex positions and faces are retained, polygons are triangulated, and named mesh objects can become separate STL parts. Materials, MTL references, texture images, UV coordinates, and color are intentionally excluded because STL has nowhere to store them.
- Private local OBJ parsing
- Polygon and quad triangulation
- Named object separation
- Multi-object STL ZIP export
- Binary STL generation
- No MTL or texture upload
What changes during OBJ to STL conversion
Polygon faces are triangulated
OBJ supports triangles, quads, and larger polygons, but STL only stores triangles. The loader triangulates supported polygon faces without adding smoothing subdivisions or new geometric detail.
Object names drive output filenames
Named OBJ objects become readable STL part names. Unsafe filename characters are replaced and repeated names receive numbered suffixes so ZIP contents remain usable.
Rendering assets are left behind
MTL files, diffuse maps, normal maps, UV coordinates, vertex color, smoothing groups, and other appearance metadata are not written into the STL result.
How to convert OBJ to STL
Step 1
Load and preview OBJ objects
Select a .obj mesh up to 100 MB and inspect its named objects, triangulated preview, dimensions, and material-loss summary.
Step 2
Confirm unit, orientation, and structure
Because OBJ is unitless, confirm the source unit and axis, choose STL output coordinates, then merge or split detected objects.
Step 3
Verify and download STL output
The exact binary STL or ZIP is reparsed; inspect the verified preview before downloading the geometry-only result.
Practical OBJ to STL use cases
Send a marketplace model to a slicer
Convert a downloadable OBJ character, prop, miniature, or terrain model into binary STL before importing it into Cura, PrusaSlicer, Bambu Studio, or another print preparation tool.
Remove appearance data for manufacturing
Create a geometry-only handoff when textures and rendering materials are irrelevant to a single-color prototype, CNC reference, mesh repair step, or print quotation.
Keep named objects as print parts
When the OBJ contains separate mesh objects, export each object as an individual STL in a ZIP so it can be oriented and manufactured independently.
OBJ and STL are different file formats
OBJ can store polygon faces, named objects, groups, material references, and texture coordinates. STL stores only triangles and surface normals. During conversion, polygon faces are triangulated while materials, textures, and OBJ-specific grouping metadata are not included in STL.
| Property | OBJ | STL |
|---|---|---|
| Geometry | Polygon mesh | Triangle mesh |
| Materials | MTL and texture references | Not supported |
| Best for | 3D modeling and interchange | Slicing and 3D printing |
Fix OBJ to STL conversion issues
- Surfaces disappear or look inside out
- Repair outward-facing normals in the source mesh. STL records surface orientation, so reversed or inconsistent OBJ winding can cause slicers to interpret shells incorrectly.
- The converted model has the wrong size
- OBJ and STL are effectively unitless in many applications. Confirm whether the source coordinates represent millimeters, centimeters, inches, or meters and correct scale in the slicer.
- The STL is not watertight
- Conversion changes the file representation but does not close holes, remove self-intersections, or create wall thickness. Use a mesh repair tool before printing open or non-manifold geometry.
OBJ to STL limitations
- MTL libraries, texture images, UV coordinates, vertex colors, smoothing groups, and rendering materials are not written to STL.
- OBJ and STL are both unitless, so the source unit and orientation must be confirmed before conversion.
- Polygon conversion triangulates faces but does not repair holes, self-intersections, reversed normals, or missing wall thickness.
- Point and line records do not define printable surfaces and are not converted.
OBJ to STL FAQ
Is the OBJ file uploaded anywhere?
No. OBJ parsing and STL generation run locally in your browser.
Will OBJ materials and textures appear in STL?
No. STL stores geometry only, so MTL materials, colors, UV coordinates, and texture images are not preserved.
What happens to OBJ polygons?
Faces with more than three vertices are triangulated because STL represents every surface as triangles.
Can one OBJ create several STL files?
Yes. When separate mesh objects are detected, the converter packages their STL files into one ZIP download.
Need the reverse conversion?
Convert an STL triangle mesh back into an editable OBJ mesh file.