3MF to STL Converter
Turn a 3MF into an STL any slicer will open, in your browser, at the right size.
Built and maintained by Matúš Koleják, Co-Founder, TechDraw AI
Updated
Drop a file here. It never leaves your browser.
No sign-up · no upload · no watermark · no file size limit · STL first, OBJ one click away
Have a different file? OBJ to STL Converter · ZIP to STL Converter · G-code to STL Converter · PLY to STL Converter
How to convert an 3MF to STL
Add your 3MF
Drop an 3MF onto the tool, or click to choose one. It is read in your browser and never uploaded.
Check the preview
Drag the model to turn it. The triangle count, the number of parts and the size in millimetres are shown under it, so a unit problem is visible before you download.
Download STL
Click Download STL. No account, no watermark, no waiting. OBJ come off the same file with one more click.
What happens to your file
The 3MF is unzipped in your browser and its model part is read as vertices and triangles. Two things happen that cheaper converters skip. The build transforms are applied, so a plate that places the same object three times comes out as three parts where they belong rather than three copies stacked at the origin, and nested components compose properly. And the model's declared unit is honoured: a 3MF authored in inches, centimetres or metres is scaled to millimetres, because STL carries no unit and every slicer reads it as millimetres. Colours, materials and slicer settings do not survive, since STL has nowhere to put them.
Starting from a photo or a drawing instead of a mesh? That is the image to STL converter, and a 2D outline becomes a solid on the DXF to STL converter.
About formats
3MF (3D Manufacturing Format) was published in 2015 by the 3MF Consortium, founded by Microsoft with Autodesk, Dassault, HP, Shapeways, SLM and others, expressly to replace STL. A 3MF is a ZIP package built on the same OPC container Office documents use, holding an XML part that lists vertices and triangles alongside the things STL never had: a declared unit, so a model authored in inches cannot be misread as millimetres; a build section with a transform per placed item, so a full plate of parts is one file that remembers where everything sits; colours, materials and textures; and room for slicer settings and supports, which is why Bambu Studio, PrusaSlicer, Cura and Orca all prefer it as a project format. The trade is that a 3MF is a package rather than a stream of triangles, so old firmware, old slicers and most online viewers still want an STL, and the mesh itself is no more accurate than the triangles put into it. Converting 3MF to STL is lossless for geometry and lossy for everything else: the shape survives, the units have to be baked in, and the colours and settings do not travel.
- Developer:
- 3MF Consortium
- Initial release:
- 2015
Frequently asked questions
How do I convert an 3MF file to STL?
Drop the 3MF onto the tool on this page and click Download STL. It is read and converted by JavaScript running in your browser, so there is nothing to install, no account to make and no queue to wait in. OBJ come off the same file with one more click.
Is this 3MF to STL converter free?
Yes. Free, no watermark, no file size limit, and no account needed to convert or to download. There is no paid tier of this tool to upsell you to.
Is my file uploaded anywhere?
No. The file is opened by code running in your browser tab and never sent to a server, which also means nothing is stored, logged or scanned. You can disconnect from the internet once the page has loaded and the converter keeps working. For a client's part under NDA that is the difference between usable and not.
Will a multi-part 3MF plate come out in the right places?
Yes. A 3MF records a transform for every item it places, and those are applied here, including nested components. That is why a plate of six parts comes out as six parts arranged as you left them rather than six copies sitting on top of each other at the origin, which is what a converter that reads only the raw mesh data will give you.
What about the units?
A 3MF declares its unit and this tool honours it. If the file says inches, centimetres, metres or microns, the geometry is scaled to millimetres on the way out, because STL and OBJ carry no unit at all and every slicer assumes millimetres. A converter that ignores this is how a model arrives 25.4 times too small.
Do colours and print settings survive?
No, and nothing can make them. A 3MF can carry colours, materials, supports and the slicer's own settings; STL and OBJ have nowhere to put any of it. Only the geometry comes across. If you need the settings, keep the 3MF as your master and treat the STL as a copy for something that cannot read 3MF.
Is there a file size limit?
None imposed by the tool. The practical limit is your own machine's memory, since the file is held in the browser tab; a few hundred megabytes is fine on a desktop and less so on a phone. Nothing is queued or throttled because there is no server involved to queue it.