Free online OBJ to 3MF converter

A slicer or fabrication application may require a packaged .3mf file instead of a standalone .obj mesh. Converting also combines model data with units, object structure, thumbnails, and—when supported—print settings in one file for sharing or further preparation.

What the OBJ format is

OBJ is a text-based 3D exchange format developed by Wavefront. It stores vertices, polygon faces, texture coordinates, and optionally surface normals. OBJ does not reliably define measurement units, so the same model can import at the wrong scale in another application.

Material assignments are normally stored in a separate .mtl file, while image textures remain separate files referenced by that material file. Keep the OBJ, MTL, and texture images together when importing a textured model.

Blender, Maya, 3ds Max, SketchUp, MeshLab, CAD conversion tools, and sculpting software commonly create or use OBJ files. It is mainly used to exchange polygon meshes between 3D applications and to distribute downloadable models.

What the 3MF format is

3MF is a ZIP-based package defined by the 3MF Consortium. Its XML model data can be accompanied by thumbnails, textures, color and material data, multiple objects, relationships, metadata, and extension data. The core format also records a unit, unlike standard OBJ files.

A 3MF file can keep a model and related manufacturing data together, reducing separate-file problems during transfer. Slicers such as PrusaSlicer, OrcaSlicer, and Bambu Studio can save printer, filament, placement, and slicing settings in 3MF project files. These settings may use application-specific extensions, so a project saved by one slicer is not guaranteed to open with identical settings in another.

Convert with PrusaSlicer

1. Install and open PrusaSlicer, then select an appropriate printer profile.
2. Choose File → Import → Import STL/OBJ/AMF/3MF, or drag the .obj file into the build area.
3. Keep the associated .mtl file and texture images beside the OBJ during import. Check the viewport for missing textures, broken faces, separate objects, and unexpected scale.
4. Open the object’s scale or dimensions controls and correct the size if the unitless OBJ imported incorrectly. Set orientation, placement, printer, filament, and other required print settings.
5. Choose File → Save Project As and save with a .3mf extension. The result is a slicer project 3MF containing the model and the current project settings.

PrusaSlicer is appropriate when the destination is another slicer or a 3D-printing workflow. Reopen the saved file in the intended application because project settings and material assignments can vary between slicers.

Convert with installed desktop software

Microsoft 3D Builder can open OBJ and save 3MF on Windows systems where the application is installed. Open the file with Open, accept or review any mesh-repair prompt, verify dimensions, then choose Menu → Save as and select 3MF. Its availability and format behavior can vary by Windows installation, so it should not be the only conversion option.

Other slicers, including OrcaSlicer and Bambu Studio, can generally import OBJ and save 3MF projects through their project-saving commands. The exact menu names and the settings embedded in the output depend on the application and version.

Convert without installing software

You can convert the file for free on 101convert.com without installing software. Upload the OBJ and, if the converter provides additional-file input, include its matching .mtl and texture files. Download the generated 3MF and open it in the target slicer to verify the geometry, dimensions, materials, and object count before printing or sharing.

Quality and compatibility limits

Conversion changes the container and representation; it does not automatically make a defective mesh printable. Check that the model is closed, has consistent face normals, contains no self-intersections, and has walls thick enough for the intended process. Automatic repair can change holes, thin walls, or sharp features.

OBJ texture and material information does not reliably become 3MF print-color or multi-material assignments. For a single-color print, choose the filament explicitly. For color or multi-extruder work, assign colors and extruders after import and inspect the sliced preview.

Confirm the imported dimensions against known measurements before saving. A 3MF package can preserve units and object relationships, but it cannot recover unit information that the original OBJ never contained.

A slicer-generated 3MF may include printer and filament settings that another program ignores. If the recipient needs only a neutral model, use a 3MF export mode without project-specific data when available, or test the file in the receiving application. Always reopen the final file and inspect its preview before manufacturing.