Convert a 3MF file to STL

Drop in a .3mf and get a plain .stl back. Unzipped and converted on your own machine, so the file never leaves your browser.

3MF → STL

Drop a 3MF file

or click to choose one. Your file never leaves your browser.

Runs locally · nothing uploaded3MF

Runs entirely in your browser. Your file is never uploaded, and there is no sign-up.

How to convert 3MF to STL

Drop your .3mf file onto the panel, or click to browse for it.
The file is read and converted on your own machine. Nothing is uploaded to a server.
Download the STL file. You get binary .stl, geometry only.

Why convert 3MF to STL

3MF is the better format, and that is exactly why people need this conversion. It is what Bambu Studio, PrusaSlicer and Cura hand you when you save a project, because it can hold colour, units, multiple objects and their arrangement on the plate. Plenty of other software never learned to read it.

Older slicers, print services that accept one upload format, mesh repair tools and a good deal of CAD software still expect an STL. Converting is how a project file becomes something those tools will open.

3MF and STL, side by side

Property	3MF	STL
Stores	Meshes, colour, materials, plate arrangement, settings	Triangles only
Units	Explicit, millimetres by default	None; slicers assume millimetres
Objects per file	Many, each named and positioned	One solid
Container	Zipped XML, compact	Raw triangle list
Introduced	2015, by the 3MF Consortium	1987, with the first stereolithography machines
Read by	Modern slicers and recent software	Effectively everything

What survives, and what does not

STL stores triangles and nothing else, so the conversion is lossy by definition. Geometry and the position of each object come through unchanged. Colour, materials, object names and any per-object slicer settings do not, because the format has nowhere to put them.

One consequence worth knowing: a 3MF holding several objects becomes a single STL containing all of them, positioned as they were arranged. If you need them as separate files, split them in your slicer before exporting rather than after.

The units problem STL never solved

STL does not record a unit of measurement. A file is just numbers, and whether they mean millimetres or inches is an assumption the receiving program makes. That is the origin of the classic problem where a model arrives at 1/25th of its intended size, or 25 times too large. 3MF states its units explicitly, which is one of the reasons it exists.

This converter writes millimetres, which is what slicers assume. If a converted model opens at the wrong scale somewhere else, the unit assumption at the far end is the first thing to check.

Where the converted file works

The output opens anywhere STL is accepted, which is close to everywhere: every slicer past and present, mesh repair tools like Meshmixer, CAD packages that import meshes, and every online print service. The converter itself runs on any current browser on Windows, macOS, Linux, Android or iOS. Nothing is installed, and because the file is unzipped and parsed locally, nothing is uploaded either.

Keep the original 3MF

Treat the STL as an export, not a replacement. The 3MF still holds your colours, object names, plate layout and print settings, none of which can be recovered from the STL later. Archive the project file and hand the STL to whatever tool demanded it.

Your file never leaves your browser

This tool is JavaScript running on your own machine. Your file is read into memory, processed there, and gone when you close the tab. It is never sent to us, so there is no upload, no queue, no retention period, and no account to create. You can disconnect from the network after the page loads and it will still work.

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Frequently asked

Can a 3MF file be converted to STL?

Yes. A 3MF carries the same triangle mesh an STL does, wrapped in a zipped XML container alongside extra data like colour, units and per-object settings. Converting keeps the geometry and drops everything STL has no way to store.

Are 3MF and STL the same?

No. Both describe a mesh, but STL stores only triangles, while 3MF also records colour, materials, units, and how several objects are arranged on the plate. 3MF is the newer format and fixes STL's known gaps, including its lack of a defined unit of measurement.

How to convert 3MF to STL in Bambu Studio?

Open the 3MF, right-click the object in the plate view, and choose Export as STL. If the file holds several objects, export them one at a time to keep them as separate STLs, or export the plate to get one combined file.

How to convert 3MF to STL in Prusa Slicer?

Import the 3MF, then use File then Export then Export plate as STL. PrusaSlicer writes the objects as they sit on the plate, so move or split them first if you want them separated.

Is my file uploaded?

No. The 3MF is unzipped and parsed in your browser, and the STL is written locally. Nothing reaches our servers, and there is no account or sign-up.

What gets lost in the conversion?

Colour, materials, object names and any per-object slicer settings, because STL cannot represent them. The geometry and its arrangement survive intact, which is the part a printer actually needs.

What is a 3MF file?

3MF is the 3D Manufacturing Format, introduced in 2015 by a consortium including Microsoft and the major slicer vendors. It is a zipped XML container that records geometry with explicit units, plus colour, materials and the arrangement of objects on the build plate. Modern slicers use it as their project format.

Will my slicer settings come through?

No. When Bambu Studio or PrusaSlicer saves a project as 3MF, the print settings ride along inside the container, and STL has nowhere to put them. The conversion hands you clean geometry; the settings stay behind in the original file, so keep it.

A 3MF with several objects: one STL or many?

One STL containing all of them, positioned as they were arranged on the plate. STL cannot mark object boundaries. If you need the parts as individual files, split them in your slicer and export them one at a time instead.

Does it work on a phone, Mac or Windows?

Yes. It is a web page, so any current browser on any operating system works. The 3MF is unzipped in memory, so extremely large project files may want a laptop rather than a phone.