Free OBJ to STL Converter
Lightning-fast OBJ to STL conversion — 100% in your browser. Your files never leave your device. Free, no watermark, no sign-up.
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Supports GLB, GLTF, OBJ, STL, FBX, PLY
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OBJ vs STL
See what transfers when converting between these two formats.
Converting OBJ to STL will lose: Textures, Materials.
| Feature | OBJ | STL |
|---|---|---|
| Geometry | ||
| Textures | ||
| Materials | ||
| Animation | ||
| Rigging |
Why convert OBJ to STL?
3D print OBJ assets
Most slicers accept STL natively and OBJ inconsistently. Convert to STL for guaranteed compatibility with Cura, PrusaSlicer, Bambu Studio, and CHITUBOX.
CAD and engineering handoff
STL is the universal mesh-interchange format for CAD packages and fabrication shops. Send STL when a client or fabricator asks for a printable file.
Slicer pre-processing
Some slicers choke on OBJ's multi-material structure. STL's single-mesh simplicity sidesteps those issues.
Tips for OBJ → STL
STL drops materials
STL has no material or texture support. The converted file is plain geometry — no colors, no UVs, no normals-only data.
Watertight mesh required
STL slicers demand manifold geometry to produce valid 3D-printer toolpaths. If your OBJ has holes, flipped faces, or non-manifold edges, expect slicing errors before you can 3D-print the part.
Multiple objects merge
OBJ's `o` and `g` directives do not survive into STL — every object bakes into one mesh. Split before converting if you need separate prints.
Binary STL by default
Fast3D exports binary STL, which is roughly 4x smaller than ASCII STL. Use binary unless your downstream tool requires ASCII.
Common issues when converting OBJ to STL
Slicer reports 'non-manifold edges'
Fix
OBJ assets from marketplaces often have minor mesh defects. Open the STL in Meshmixer's Analyze → Auto Repair, or Windows 3D Builder's repair tool, then re-export.
Printed model has the wrong scale
Fix
OBJ does not store units. STL inherits the raw coordinates. If the OBJ was modeled in meters but the slicer expects millimeters, scale by 1000× in the slicer.
STL file is huge
Fix
OBJ assets can have very dense meshes. Decimate in Blender before converting — typically a 50% decimation is invisible on printed parts.