OBJ to 3MF Converter

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

  • Files stay on your device
  • Free, no sign-up
  • Units and up axis handled
  • Batch and .zip

Drop an OBJ file to convert

One file, many, or a .zip

In: STL · STEP · IGES · OBJ · 3MF · GLB · glTF · PLY · FBX · DAE · 3DS · AMF · VRML · ZIP

Converted on your device. Nothing is uploaded.

    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 from OBJ to 3MF

    Worked out from what each format can store and what this converter writes. Nothing is changed silently: the preview shows the size and orientation before you download.

    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 to 3MF: what actually happens

    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 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.

    OBJ at a glance

    Wavefront OBJ · .obj

    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

    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.

    Open OBJ files in the viewer

    3MF at a glance

    3D Manufacturing Format · .3mf

    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

    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.

    Open 3MF files in the viewer

    Tips for OBJ to 3MF

    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.

    OBJ to 3MF 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.