Browser-local conversion

3MF to STL Converter

Export the entire supported placed 3MF build or one selected top-level placed item as binary STL in millimetres, locally without upload.

Choose a 3MF file

Converted locally in your browser — your file is not uploaded.

Files must be 25 MiB or smaller so conversion remains safe for this browser.

Drag and drop a file here, or choose a file

Try an example

Question to explore

How do resources, placements and declared units affect the STL export?

Settings: 3MF uses declared units. Conversion offers entire-build or single placed-item scope in millimetres; generate and verify explicitly.

Example file

Downloads this public control, then opens it locally. Your own file can still be chosen above.

Read the explanation · Download and compare controls · Methods and processing

Keep the original 3MF

3MF to STL is a geometry-only export. Keep the original 3MF if you need its units, separate build items, colours, materials or print settings.

An entire-build export combines its placed triangles into one STL; a selected-item export includes that placement and its supported nested components. The original editable assembly cannot be reconstructed from it.

Read how to convert 3MF to STL · Open a 3MF in the Viewer · Choose a print file format

Verify a geometry-only export

Choose combined or separately delivered placements before selecting scope. If the receiving model looks moved or resized, compare units, transforms and receiving placement; matching outer bounds alone cannot establish preservation of every opening or part.

Geometry and supported transforms: The selected placed build or item is flattened into triangles. Overlapping shells are not Boolean-unioned.
Units: Physical coordinates are converted to millimetres; STL stores no unit declaration. Open the saved STL with a millimetre assumption.
Object identities and editable placements: Separate resource and build-item records are lost. Selection chooses one top-level item, not an automatic ZIP of separate STL parts.
Colours and material assignments: Not preserved in this binary STL export.
Printer and slicer settings: Not exported. Keep the original project and use its producing slicer for settings.

The converter resolves supported build geometry, applies component and build transforms, converts physical coordinates to millimetres and writes one binary STL. Choose the entire supported placed build or one top-level placed item. Isolation in the viewer does not change this choice. Separate placements become triangles in one file rather than editable build-item records.

Keep the original 3MF and note its declared unit and intended objects.
Download the declared-inch transformed example and convert it locally.
Open the STL with a millimetre assumption: expect 25.4 mm spans and X coordinates from 50.8 to 76.2 mm.
Repeat with the two-placed-cubes example: inspect both cubes and the 60 mm total X span.
Compare dimensions and placement in the destination slicer before printing.

STL drops the package's unit declaration, object names, property assignments and application-specific settings. It does not Boolean-union overlapping shells. Unsupported build data should be resolved in the producing application; stop if a required object disappears. Keep project information separately from this mesh derivative.