Convert STL to OBJ Online — Edit 3D Print Files

Convert STL files to OBJ format to edit 3D print models in Blender, Maya, 3ds Max, or other digital content creation (DCC) tools. STL is a geometry-only format used for 3D printing. OBJ is a universal interchange format with better software compatibility and editing capabilities.

Process files locally in your browser using WebAssembly — no upload, privacy-friendly, instant download. Works with STL files from Thingiverse, MyMiniFactory, Printables, or your own 3D scans.

Perfect for editing downloaded 3D print models, adding details before printing, or combining multiple STL parts into a single model.

Drag STL file here, or click to upload

Supports .stl files up to 50MB

Technical Details

What Changes During Conversion

Converting STL to OBJ is mostly lossless. Geometry is fully preserved. The converter welds shared vertices (STL stores disconnected triangles) to create proper mesh topology for editing. Face normals are converted to vertex normals for smooth shading. No materials are added (STL has no material data).

File Size

OBJ files are typically smaller than STL because OBJ uses indexed vertices instead of duplicating vertex data. A 10 MB ASCII STL becomes roughly 6-8 MB OBJ (40% reduction). A 5 MB Binary STL becomes roughly 4-5 MB OBJ.

Common Use Cases

Edit Downloaded 3D Print Models

Downloaded a figurine from Thingiverse but need to adjust proportions? Convert STL to OBJ, edit in Blender (extrude, bevel, boolean operations, add text/logos), then export back to STL.

Combine Multiple STL Parts

Multi-part models (figurines, modular designs) often come as separate STL files. Convert each to OBJ, merge in Blender, then export the final model.

Add Materials for Rendering

Need to render your 3D print model for marketing or portfolio? STL has no material support. Convert to OBJ, assign PBR materials in Blender, then render in Cycles or Eevee.

STL vs OBJ: Quick Comparison

FeatureSTLOBJ
GeometryTriangles (disconnected)Polygons (indexed, shared)
NormalsFace normals (flat)Vertex normals (smooth)
MaterialsNot supportedSupported (.mtl)
Primary Use3D printingModeling, interchange
File SizeLarger (duplicated verts)Smaller (indexed verts)
EditingPoor (disconnected mesh)Excellent (proper topology)

Use STL for 3D printing (slicer input). Use OBJ for modeling, editing, rendering, and archiving.

Frequently Asked Questions

Yes! Import the OBJ into Blender (File > Import > Wavefront). The mesh will have proper vertex indexing (unlike STL's disconnected triangles), so you can use Edit Mode operations like extrude, bevel, loop cut, and apply modifiers like subdivision, mirror, and boolean.
No. The converter preserves geometry only. The OBJ will have no .mtl file. In Blender, the imported mesh will be gray. You can manually assign materials after import.
No. The converter preserves vertex positions exactly. However, STL is often in millimeters while OBJ/Blender uses generic units. If your model looks 1000x too large or too small, scale by 0.001 or 1000.
Legally: Check the model's license (most Thingiverse models are Creative Commons -- respect attribution, non-commercial, share-alike terms). Technically: Yes. Convert STL to OBJ, edit in Blender, then export back to STL.
STL stores disconnected triangles (each vertex duplicated per face). OBJ uses indexed vertices (each unique vertex stored once). OBJ is typically 30-50% smaller than ASCII STL, and comparable to Binary STL.

Related Converters

OBJ to STL Converter

Done editing? Convert your OBJ back to STL to send the model to your 3D printer.

STL to GLB Converter

Want to display your 3D print on the web? Convert STL to GLB for Web3D visualization.