# OBJ to 3MF Converter

> Turn colored OBJ models into 3MF with their material colors as filament colors, ready for Bambu Studio, OrcaSlicer or PrusaSlicer.

Page: https://printpal.io/convert/obj-to-3mf
Updated: 2026-11-12
Use it: open https://printpal.io/convert/obj-to-3mf in a browser and drop a file. Free, no account, files are processed locally and never uploaded.

An OBJ with an .mtl assigns a color to each group of faces. The converter maps every material color to a slicer filament (up to 16) and paints the triangles in the 3MF, so Bambu Studio and OrcaSlicer open it with the colors already assigned. Drop the .obj with its .mtl, or a .zip.

Texture colors and vertex colors are not filament colors, so textured OBJs come out single-color; the [AMS converter](https://printpal.io/tools/ams-converter) reduces textures to filaments. The model is turned from Y up to Z up and written in millimetres; set the file units first if it was built in metres.

## How to convert OBJ to 3MF

1. **Drop your OBJ files.** Drop the .obj with its .mtl and texture images, or a .zip of the folder.
2. **Check the preview.** The model appears at the size and orientation it will have. Fix the file units, up axis or size under Size, units and orientation if needed.
3. **Choose 3MF options.** Keep parts as one object for a simple print, or tick separate objects to move them independently in the slicer.
4. **Convert and download.** One file downloads straight away. A batch gives a download per file and one .zip of all of them.

## What carries over

| | Result |
|---|---|
| Geometry | Every face is kept; quads and n-gons are split into triangles. |
| Color | Material, face and painted colors become slicer filaments (up to 16). Textures and vertex colors do not, so those models come out single-color. |
| Units | OBJ has bare numbers, so they pass through as millimetres: 1 unit becomes 1 millimetre. If the preview size is wrong, set the file units. |
| Orientation | Turned from Y up to Z up, so it stands on the plate in a slicer. |
| Objects | One object by default, or one 3MF object per part. Placed on Z = 0 and centered on a 256 mm plate. |

## OBJ at a glance (Wavefront OBJ)

OBJ came out of Wavefront Technologies' animation software and became the plain-text lingua franca of 3D. The geometry is in the .obj; colors and texture references live in a companion .mtl file, which is why OBJs so often arrive grey.

- **Stores:** Vertices, faces (triangles, quads, n-gons), UVs and normals as text
- **Color:** Materials and textures in a separate .mtl file; vertex colors as an unofficial extension
- **Units:** None, the numbers are bare
- **Up axis:** Y by convention (Blender, Maya, most 3D apps)
- **File size:** Text: about a binary STL's size for bare geometry, up to twice that with UVs and normals
- **Opens in:** Blender, Maya, 3ds Max, ZBrush, Cinema 4D, game engines, most slicers

## 3MF at a glance (3D Manufacturing Format)

The 3MF Consortium (founded 2015 by Microsoft, Autodesk, HP and others) designed 3MF to replace STL for printing. Bambu Studio, OrcaSlicer and PrusaSlicer save whole projects in it: plates, painted colors and print settings alongside the meshes.

- **Stores:** A zipped XML model: shared vertices, objects with transforms, a build plate
- **Color:** Materials and per-triangle colors; slicers add painted filament colors
- **Units:** Declared in the file, millimetres by default
- **Up axis:** Z
- **File size:** Compressed, usually under half of a binary STL
- **Opens in:** Bambu Studio, OrcaSlicer, PrusaSlicer, Cura, Creality Print

## Tips

- **Fewer colors** Each filament change costs purge and time. Merge similar materials before converting.
- **Separate objects** Tick separate objects to move each OBJ group independently on the plate.
- **Check the size** The preview shows the size the 3MF will have in millimetres.

## FAQ

### Does OBJ to 3MF keep colors?

Material colors from the .mtl, yes, as filaments. Textures and vertex colors, no; use the AMS converter for those.

### How many colors can the 3MF have?

Up to 16, the limit of Bambu Studio and OrcaSlicer painting.

### Will PrusaSlicer show the colors?

Yes, the colors are also written as PrusaSlicer MMU segmentation.

### Is the converter free? Are there limits?

Free, with no sign-up, watermark or file count limit. Batches and files of a few hundred MB work on most laptops; the only limit is your device's memory.

### Are my files uploaded?

No. Files are read and written by JavaScript and WebAssembly in your browser and never sent to PrintPal. The STEP and IGES reader is the only extra download, once, from a public CDN.

## Related

- [OBJ to STL Converter](https://printpal.io/convert/obj-to-stl)
- [3MF to STL Converter](https://printpal.io/convert/3mf-to-stl)
- [OBJ to GLB Converter](https://printpal.io/convert/obj-to-glb)
- [3MF to OBJ Converter](https://printpal.io/convert/3mf-to-obj)
- [OBJ to USDZ Converter](https://printpal.io/convert/obj-to-usdz)
- [STL to OBJ Converter](https://printpal.io/convert/stl-to-obj)
- [STL to 3MF Converter](https://printpal.io/convert/stl-to-3mf)
- [STEP to OBJ Converter](https://printpal.io/convert/step-to-obj)
- [3D model viewer](https://printpal.io/tools/3d-model-viewer)
- [3D model converter](https://printpal.io/tools/3d-model-converter)
- [Mesh Repair](https://printpal.io/tools/mesh-repair)
- PrintPal for LLMs: https://printpal.io/llms.txt