Convert STL to OBJ Online (Free & Secure)
iLove3DM converts STL files to OBJ online and free: .stl in, .obj out. STL is a binary (or ASCII) list of unindexed triangles, while OBJ is plain ASCII text with a companion .mtl material file; the converter bridges the two using GLB as an intermediate scene.
Select .STL file
or drag & drop .stl file here
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⚡ AI Summary & Quick Answer
iLove3DM converts STL files to OBJ online and free: .stl in, .obj out. STL is a binary (or ASCII) list of unindexed triangles, while OBJ is plain ASCII text with a companion .mtl material file; the converter bridges the two using GLB as an intermediate scene.
Moving a print-ready mesh into a general modelling format lets you re-sculpt, retexture or rig a part that started life as a printable file. STL (.stl) is a binary (or ASCII) list of unindexed triangles. It holds raw triangle facets without shared vertices or UV coordinates and is most often opened in Cura, PrusaSlicer, and Bambu Studio. OBJ (.obj) is plain ASCII text with a companion .mtl material file, holding polygons (triangles, quads and n-gons) with shared UV and normal pools, and is typically used in Blender, Maya, and 3ds Max.
Because STL uses no material information while OBJ uses Phong-style MTL materials (diffuse, specular, ambient), the converter reads your scene, applies the mapping described below and writes a clean .obj file. Everything runs in your browser or an isolated, auto-purged instance, so models stay private.
.stlAbout STL (Stereolithography)
The standard format for 3D printing and additive manufacturing. Defines surface geometry using unstructured triangulated facets.
- Structure: a binary (or ASCII) list of unindexed triangles
- Materials: no material information
- Units: unitless (slicers usually assume millimeters)
- Axis: Z-up, matching 3D printer coordinates
- Opens in: Cura, PrusaSlicer, Bambu Studio, Fusion 360 or MeshLab
.objTarget format: OBJ (Wavefront)
Universal geometry definition format supported by almost every 3D modeling and rendering software.
- Structure: plain ASCII text with a companion .mtl material file
- Materials: Phong-style MTL materials (diffuse, specular, ambient)
- Units: unitless (the importing application decides the scale)
- Axis: conventionally Y-up, but not enforced
- Opens in: Blender, Maya, 3ds Max, ZBrush or MeshLab
What happens to your data in STL → OBJ conversion
Conversion route: STL → GLB → OBJ (parsed into a GLB scene, then exported as OBJ).
| Aspect | Result | Outcome |
|---|---|---|
| Geometry | Preserved | STL stores raw triangle facets without shared vertices or UV coordinates; OBJ stores polygons (triangles, quads and n-gons) with shared UV and normal pools. Surfaces are retriangulated where needed and positions, normals and UV coordinates are carried across. |
| Materials | Not applicable | STL carries no material data, so the OBJ output uses a neutral default material. |
| Textures | Not applicable | STL has no texture support, so there is nothing to carry over; add textures after conversion if you need them. |
| Vertex colours | Not applicable | STL has no vertex colour data, so the output is uncoloured at vertex level. |
| Animation | Not applicable | STL is a static format, so the OBJ result is a single static pose. |
| Units & scale | Adapted | STL uses unitless (slicers usually assume millimeters); OBJ uses unitless (the importing application decides the scale). Check the scale in your target application, and use the Scale tool if the model looks too big or too small. |
| Orientation | Adapted | STL is Z-up, matching 3D printer coordinates and OBJ is conventionally Y-up, but not enforced. The converter writes a consistent orientation, but verify the up axis in your target software. |
Expect the OBJ file to be roughly 1.6x larger than the STL source, because OBJ is large, because every coordinate is stored as text.
Why convert STL to OBJ?
Why leave STL
People most often convert from STL when they are adding materials and textures to a printable model. Other common cases include previewing a printable part on the web or in AR and sharing a CAD export with people who have no slicer. In STL → OBJ specifically, preserved: geometry; adapted: units & scale and orientation. Expect the OBJ file to be roughly 1.6x larger than the STL source, because OBJ is large, because every coordinate is stored as text.
Why choose OBJ
OBJ is the right target when you are archiving a model in a simple, inspectable format. It also fits scenarios such as sending geometry to sculpting and texturing software and exchanging a mesh with almost any 3D application. Moving a print-ready mesh into a general modelling format lets you re-sculpt, retexture or rig a part that started life as a printable file.
Where the result opens
After conversion you can open the .obj file in Blender, Maya, 3ds Max, ZBrush or MeshLab.
Step-by-Step Guide: STL → OBJ
- 1
Upload your .stl file
Drag your STL model onto the converter or click to browse. There is no texture or UV support; no extra files are required.
- 2
Check your free quota
Free accounts can run a few conversions per day; signing in unlocks tracking of your remaining uses. No watermark is ever added.
- 3
Convert to OBJ
Press the Convert to OBJ button. The pipeline follows STL → GLB → OBJ (parsed into a GLB scene, then exported as OBJ), which usually takes a few seconds for models under 100 MB.
- 4
Download the .obj file
Your OBJ file downloads automatically. Open it in Blender and Maya to confirm scale and orientation.
Tips for STL → OBJ
- Colour and texture data are discarded (STL source).
- Missing .mtl or texture files turn a model grey (OBJ target).
- Always verify real-world size: STL is unitless (slicers usually assume millimeters), while OBJ is unitless (the importing application decides the scale).
Frequently Asked Questions
How do I convert STL to OBJ without losing quality?
Upload the .stl file and press convert; the route is STL → GLB → OBJ (parsed into a GLB scene, then exported as OBJ). Geometry is carried over exactly; no materials exist in the source, and no textures are involved.
Does STL to OBJ conversion keep colours?
STL has no vertex colour data, so the output is uncoloured at vertex level.
Why does my OBJ model look the wrong size or rotation?
STL uses unitless (slicers usually assume millimeters); OBJ uses unitless (the importing application decides the scale). Check the scale in your target application, and use the Scale tool if the model looks too big or too small. STL is Z-up, matching 3D printer coordinates and OBJ is conventionally Y-up, but not enforced. The converter writes a consistent orientation, but verify the up axis in your target software.
Will the OBJ file be bigger or smaller than my STL file?
Expect the OBJ file to be roughly 1.6x larger than the STL source, because OBJ is large, because every coordinate is stored as text.
What software can open the converted OBJ file?
OBJ files open in Blender, Maya, 3ds Max, ZBrush or MeshLab. If you need to go back, use the OBJ to STL converter.
Is it safe to upload my STL model?
Yes. Files are processed in your browser or on isolated instances and purged right after conversion. They are never used to train AI models, and no watermark is added.