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Your .obj is converted on your own computer and never uploaded, so client and unreleased work stays with you.
OBJ to STL Converter
Turn OBJ files from Blender, Maya or CAD into binary STL for 3D printing. Upright, to scale, nothing uploaded.
Loading 3D preview
Drag to rotate
Converted in your browser. Files are never uploaded.
Continue with your model
Inspect the OBJ first, check the STL after, or pack parts for your slicer.
How to convert OBJ to STL
- 1
Add your OBJ files
Drop one .obj or a whole folder's worth. The .mtl and texture files are not needed.
- 2
Check the preview
The model lands on a build plate at its real size. Split objects or resize the longest side if needed.
- 3
Download the STL
Save a binary STL that opens in Bambu Studio, PrusaSlicer, Cura and OrcaSlicer.
Why use this OBJ to STL converter
Built for OBJ exports from Blender, Maya and CAD that need to reach a slicer.
Batch convert
Add many OBJ files at once and download every STL together in one ZIP.
Size shown before you download
The model sits on a build plate with its width, depth and height in millimeters or inches, plus its triangle count.
Large files welcome
Files up to 300 MB each are accepted, so dense sculpts and detailed CAD exports fit.
What changes when OBJ becomes STL
OBJ can describe polygons, materials and textures. STL only stores triangles, which is all a slicer needs.
Kept
- Every object and group in the OBJ
- Quads and n-gons, split into triangles
- The size in your OBJ, read as millimeters
- Up direction, turned from Y-up to the Z-up slicers use
Left behind
- Materials from the .mtl file
- Textures and UV coordinates
- Vertex normals and smoothing groups
- Lines, curves and free-form surfaces
OBJ to STL questions
Answers about .mtl files, scale, orientation, holes and cost.
Do I need the .mtl file?
No. STL cannot store materials or colors, so only the .obj itself is read. Leave the .mtl and textures out.
My model came out tiny or huge. Why?
OBJ has no unit. Blender often exports in meters, so a 0.1 unit model becomes 0.1 mm. Turn on Resize longest side and type the size you want in millimeters.
Why is my model lying on its back in the slicer?
It should not be after conversion: OBJ files usually use Y as up, and the converter turns them to Z-up for slicers. If your OBJ was already Z-up, rotate it once in the slicer.
Will the STL be watertight?
The converter keeps your mesh exactly as it is. If the OBJ had holes, the STL will too. Open it in the OBJ viewer first to check for open edges.
Is the OBJ to STL converter free?
Yes, with no sign-up, no limit and no upload. Everything runs in your browser.