Mesh convert
Upload a Wavefront OBJ file and download it as STL.
Everything runs in your browser — your files are never uploaded. STEP/IGES use the OpenCASCADE engine (a one-time ~7 MB download) and are tessellated into a mesh, so the result is a surface model, not editable CAD history.
OBJ (Wavefront OBJ) and STL (Stereolithography) are both 3D file formats, but they serve different purposes. OBJ files store geometry, texture coordinates, and normals in a human-readable text format, making them ideal for design and animation work. STL files store only the triangular surface mesh as binary or ASCII data, which is the standard input format for 3D printers and many CAD applications. Converting OBJ to STL lets you take a detailed design and prepare it for manufacturing or analysis in tools that require the STL format.
The converter reads your OBJ file's vertex data, faces, and normals, then tessellates (breaks down) the geometry into triangles and exports it as an STL mesh. If your OBJ contains multiple objects or groups, the tool consolidates them into a single STL model. The conversion preserves the model's scale and spatial relationships, though any texture or colour information in the OBJ is discarded because STL is a geometry-only format.
| Input | Result | Notes |
|---|---|---|
| OBJ file: 45 KB mechanical bracket with 2,340 vertices, 4,680 faces | STL file: 187 KB (ASCII) or 56 KB (binary) | STL binary is compact; ASCII is human-readable but larger. File size depends on mesh density. |
| OBJ file: character model with smooth shading normals, 5 separate groups | Single consolidated STL mesh with all 5 groups merged | STL doesn't support separate objects, so multi-part OBJs become one unified mesh. |
| OBJ file: 2.5 MB architectural model with 150,000 vertices | STL file: 8.9 MB (ASCII) or 2.1 MB (binary) | High-polygon models produce larger STLs. Consider decimation if file size is a concern for 3D printers. |
No. OBJ and STL both preserve spatial coordinates. If your OBJ is measured in millimetres, the STL will be too. Check your STL in the target software (Cura, Prusa Slicer, etc.) to confirm scale before printing.
Yes, but it requires a separate STL-to-OBJ tool. STL to OBJ is straightforward because both are mesh-based; you won't recover lost textures or materials, but geometry transfers perfectly.
OBJs over 100 MB may take longer. Split the file into smaller parts in Blender, convert each part separately, then re-combine the STLs in your slicer or CAD tool.
This tool does not store uploaded files permanently. Files are processed in-memory and deleted after download. For maximum privacy, close your browser tab after downloading.
Yes. OBJs with multiple materials (mtllib references) are converted to a single merged STL mesh. All separate object groups are combined into one printable model.
Binary STL is compact (80-byte header + 50-byte records per triangle) and is the industry standard for 3D printing. ASCII STL is human-readable and editable in a text editor, but typically 5–10× larger in file size.