OBJ to 3MF converter
Drop your .obj file — we convert it to .3mf right in your browser. Files never leave your computer.
Why convert OBJ to 3MF?
Pulling a Blender / ZBrush OBJ into a modern slicer with unit metadata intact. 3MF cleans up the OBJ's chronic unit ambiguity (OBJ has no unit header at all) and gives the slicer something it can scale correctly from first import.
Who runs this conversion
Blender printers preparing a digital sculpture for FDM, ZBrush artists handing a retopologised mesh to a slicer, makers consolidating their print libraries on 3MF instead of STL.
Things that commonly go wrong
- OBJ has no unit tag — you need to know whether the source is in millimetres before accepting the 3MF scale.
- N-gons from Blender triangulate during load, which can create fan patterns visible on flat regions after print.
- Materials and textures do not transfer; 3MF output here is geometry-only by design.
Technical note for this tool
OBJLoader → triangulated BufferGeometry → 3MF package (core spec, zip + 3dmodel.model XML). Tagged as millimetres.
OBJ vs 3MF— what's the difference?
Human-readable Wavefront mesh format — ubiquitous in 3D graphics, game art, and asset pipelines. Pairs with a .mtl material file.
- Supported by virtually every 3D tool (Blender, Maya, 3ds Max, Unity, Unreal…)
- Plain-text, easy to diff and hand-edit
- Keeps UV coordinates and vertex normals, unlike STL
- Material references via companion .mtl file
- Text format — larger on disk than binary meshes
- No scene hierarchy, no animation, no skeletons
- Materials live in a separate file; easy to lose
Modern successor to STL for 3D printing — carries units, colours, materials, and multiple bodies in a zipped XML package.
- Real-world units baked in (no more "is this mm or inches?")
- Multi-material, multi-colour, and per-body metadata
- Compact zipped payload — smaller than equivalent STL
- Not every slicer reads 3MF yet (most do now — Bambu, Prusa, Cura)
- Less tooling for mesh editing compared to STL
Deeper context on the formats
OBJ — where it came from
Created by Wavefront Technologies in the late 1980s for their Advanced Visualizer software. When Wavefront was absorbed into Alias (then Autodesk), the format stayed public and became the lingua franca for academic 3D research, hobbyist modeling, and early game art. Its ASCII simplicity is why every graphics textbook still ships an OBJ example file.
- The .mtl material file must travel with the .obj — ship them as a zip or the textures will vanish on the other side.
- Negative indices and per-face normals exist in the spec but many importers silently misread them. Re-export from a round-trip through Blender if a downstream tool complains.
- Triangulate before export if the target is a game engine — Unity and Unreal OBJ importers choke on n-gons.
Real-world use: Computer-graphics research papers still use OBJ as the reference format for meshes. Hobbyist marketplaces (TurboSquid, CGTrader free tiers) distribute OBJ + MTL packs. Photogrammetry pipelines (Meshroom, RealityCapture) output OBJ as the portable intermediate. It is still the safest format to hand to a stranger who just said "I need a 3D model."
3MF — where it came from
The 3MF Consortium (Microsoft, HP, Autodesk, Dassault, Shapeways, and others) published version 1.0 in 2015 specifically to replace STL's forty-year-old limitations. Bambu Studio and PrusaSlicer adopted it aggressively because it is the only portable way to ship multi-colour / multi-material print projects.
- The format is zipped XML — renaming .3mf to .zip and inspecting the contents is fair game for debugging.
- Extensions (materials, slice, production) are optional; a slicer may read the geometry but drop the colour metadata.
- Some slicers treat "print-ready 3MF" (baked supports and toolpaths) differently from "design 3MF" (just the mesh). Check the export dialog for the right flavour.
Real-world use: Multi-material Bambu X1C / A1 prints, Prusa MMU workflows, paint-by-face colour printing (PrusaSlicer, Bambu Studio), and Windows 3D Builder. Anywhere an STL would lose information, 3MF has quietly taken over.
How to convert OBJ to 3MF
- 1Drop a .obj file onto the page. Companion .mtl is optional — geometry alone is enough for printing.
- 2Preview the mesh in 3D and verify the triangle count before converting.
- 3Click Download .3MF. Load directly in Bambu Studio, PrusaSlicer, Cura, or OrcaSlicer.
FAQ
Why convert OBJ to 3MF for printing?
OBJ is fine for DCC work but slicers prefer 3MF because it carries units, a clean scene graph, and multi-body data. Converting OBJ to 3MF before slicing eliminates the "is this mm or inches?" ambiguity.
Are my textures or materials kept?
The geometry is preserved exactly. Materials inside .mtl are stripped — 3MF for printing normally carries colour at the body level, which most slicers set in their own UI after import.
Does OBJ size matter?
Text-based OBJs can be large. The 3MF we write zips the XML payload, so expect the output to be significantly smaller than the source .obj.
What coordinate system does the 3MF use?
The converter assumes OBJ coordinates are millimetres (the 3D-printing default). If your source is in another unit, scale the print in the slicer after loading.
Is anything uploaded?
No. The OBJ is parsed in your browser and re-packaged as 3MF locally. Your file never leaves your device.