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GLBKit

3MF to STL Converter

Convert a 3MF print package to binary STL for slicers that only accept STL. Colour and unit data are lost. Runs in your browser.

Drag & drop your 3MF file here

or click to browse

Supported Formats

.glb.gltf.obj.fbx.stl.ply.3mf.off.zip

Format Information

Source Format

3MF.3mf

3MF (3D Manufacturing Format)

3MF is the modern replacement for STL, built for 3D printing and industrial additive manufacturing. It is an OPC package — a ZIP container holding XML metadata and mesh parts — which is why it can carry colour and material information that STL cannot.

What it carries: Triangle geometry, per-vertex colour and a base material colour. This converter writes geometry and colour; image textures and the wider 3MF material model are not written, and textures inside an imported 3MF are not read.

Open a 3MF file in the viewer

Target Format

STL.stl

STL (Stereolithography)

STL is an additive-manufacturing format from the 1990s: a flat list of triangles and nothing else. It has no concept of a scene, a material or a texture, which is why it is the lingua franca of 3D printing and also its most lossy interchange format.

What it carries: Triangle positions and, optionally, one facet normal per triangle. No UVs, no vertex colours, no materials, no node hierarchy, no animation.

Open a STL file in the viewer

About this conversion

The compatibility conversion for printing. A 3MF is written as a binary STL, which every slicer understands — at the cost of everything 3MF added over STL in the first place.

Why convert 3MF to STL

  • Feed a 3MF to a slicer that only accepts STL.
  • Match a printer, supplier or workflow that has not moved to 3MF.
  • Produce a minimal, universally accepted print file.

What happens during the conversion

Geometry

The 3MF triangles are written as a binary STL with facet normals. Part structure is flattened into a single triangle list and transforms are baked into the positions.

Materials and textures

None survive. STL has no colour, material, texture or UV field, so the 3MF's per-vertex colour and base material colour are both discarded.

Common use cases

  • Sending a 3MF to an STL-only slicer.
  • Meeting a legacy print supplier's file requirement.
  • Producing a minimal print file for a simple workflow.

Limitations of this conversion

  • All colour and material data is lost. If the 3MF was multi-colour, that is the whole reason to use 3MF, and converting to STL gives it up.
  • Part structure is flattened into one mesh.
  • STL carries no unit metadata, so the 3MF's own unit setting is dropped and the scale has to be confirmed in the slicer.

How to convert 3MF to STL

Three steps in the browser. Nothing is uploaded to a server, so an unwieldy file is limited only by your own device's memory.

1
STEP 1

Upload your .3mf

The 3MF package is read directly. Nothing about the colour survives, because STL has nowhere to put it.

2
STEP 2

Convert to STL

Geometry is triangulated and written as a binary STL.

3
STEP 3

Check the scale in your slicer

STL has no unit field, so the 3MF's unit attribute is lost and the scale must be set in the slicer.

Related tools and formats

Frequently Asked Questions

Questions people ask when turning 3MF files into STL.

Looking for a different direction? See every supported conversion.