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Free 3D converter

Convert 3MF to STL

Drop a 3MF file and download it as STL, scaled and set on the build plate. The conversion runs in your browser, so the file never leaves your device. It keeps the exact shape and a real size in millimetres.

Free, no sign-up, and your file stays on your device.

Drop a 3MF file here

Converted to STL in your browser. Nothing is uploaded.

GLB, glTF, OBJ, STL, PLY, FBX or 3MF, up to 300 MB. Add .mtl, .bin and texture files alongside.

What carries over from 3MF to STL

Checked against what the converter writes, not just what the formats allow.
Shape (triangles)
Kept exactly
UV coordinates
Dropped: STL can't store it
Colour texture
Dropped: STL can't store it
PBR maps (roughness, metalness, normal)
Not in 3MF
Vertex colours
Dropped: STL can't store it
Animation
Not in 3MF
Separate parts
Dropped: STL can't store it
Size and units
Kept in millimetres, or scaled to the height you set.
Up direction
Turned Z up and set flat on the build plate.

How to convert 3MF to STL

  1. Add your 3MF

    Drop the .3mf file or choose it from your device.

  2. Check the preview

    Turn the model, check its triangle count, and set the height you want to print in millimetres.

  3. Download the STL

    The .stl is written in a second or two for most models.

When to convert 3MF to STL

  • To 3D print it

    Every slicer reads STL. The 3MF becomes a plain list of triangles, sized in millimetres and ready to slice.

  • To send it to a print service

    Print bureaus and online quote tools ask for STL more than anything else.

The two formats

3MF

3D Manufacturing Format

3MF is an open, zip-based XML format from the 3MF Consortium (founded in 2015) built to replace STL for printing. Unlike STL it records units, so a model always opens at the right size.

Usually comes from
Bambu Studio and PrusaSlicer projects, MakerWorld and Printables downloads
Opens in
every major slicer: Bambu Studio, PrusaSlicer, OrcaSlicer, UltiMaker Cura and Lychee
Units
Recorded in the file (millimetres when written here)
Up axis
Z up

STL

Stereolithography

STL was created by 3D Systems in 1987 for its stereolithography printers. It stores a surface as a list of triangles and nothing else: no colour, textures or units.

Usually comes from
print libraries such as Printables and Thingiverse, CAD exports and 3D scanners
Opens in
every slicer (Bambu Studio, PrusaSlicer, OrcaSlicer, UltiMaker Cura and others) and most 3D apps
Units
None recorded (read as millimetres by slicers)
Up axis
Z up by convention

Questions

Something else? Ask us and a person will answer.

Is this 3MF to STL converter free?

Yes. There is no account, watermark or limit on conversions. It accepts files up to 300 MB; how large a model your browser can handle depends on your device's memory.

Is my file uploaded?

No. The conversion runs in your browser with the open-source three.js loaders and exporters, so your 3MF never leaves your device.

Why is my STL the wrong size in the slicer?

The converter shows the output size in millimetres before you download. Set a height to scale it, or keep the original size.

Will colours and textures be kept in the STL?

No. STL stores only triangles. For a full-colour print, keep the 3MF and colour it in your slicer, or export to OBJ with its texture.

Is the model watertight and printable?

The converter keeps the shape exactly; it doesn't repair it. Slicers fix small holes automatically. For meshes with many open edges, run them through your slicer's repair or Blender's 3D Print Toolbox first.

Can I make a 3D model from a photo instead?

Yes. PhotoGenius turns a photo or a text prompt into a textured GLB with Rodin Gen-2.5, Rodin Gen-2.5 Fast, Tripo H3.1, TRELLIS.2, Rodin Gen-2 or Hunyuan3D 3.1, which you can then convert here. See Image to 3D model.

Turn a photo into a 3D model

Rodin Gen-2.5, Rodin Gen-2.5 Fast, Tripo H3.1, TRELLIS.2, Rodin Gen-2 or Hunyuan3D 3.1 builds a textured GLB from one image. The price shows before you run it.