Convert 3MF
to STL.

Updated 2026-10-17

To convert 3MF to STL, drop the .3mf into the converter below and download the .stl. Project files saved by Bambu Studio, OrcaSlicer or PrusaSlicer, which keep each object in its own part of the package, are read in full. Every object comes out together in one STL, where the 3MF placed it. 5 conversions a day are free with no account. If you have the slicer that made the file, its Export menu writes STL too.

5 conversions a day with no account. No card, no install. In your browser: no daily limit, and the file is never uploaded.

No account needed
Drop a 3MF file.3mf · up to 200 MB

On our servers. No account: deleted within 24 hours. Signed in: kept until you delete them. Never shared or used for training.

ResultMesh

The shape is unchanged — same triangles, same dimensions. Only the container changes.

Changes3MF → STL

What changes between 3MF and STL

A 3MF is a zipped package: meshes, their placement on the build plate, the unit, and often colours, materials and a whole slicer project with print settings and plate layout. An STL is a single list of triangles. Converting keeps the triangles and lets go of everything else.

So the shape is untouched: no triangle is moved, added or smoothed, because both sides are meshes. What goes is colour and paint, materials, object names, print profiles and support or seam painting from the slicer.

Two things to check. STL has no room for a unit; the numbers are written as the 3MF held them, which is millimetres in nearly every 3MF a slicer writes, so pick millimetres if your software asks. And all the objects arrive as one STL, in their places on the plate. If you need one part alone, export it from the slicer, or split it in your mesh tool afterwards.

HowThree steps
  1. Drop your .3mf file above — up to 200 MB without an account.
  2. STL is already selected as the output.
  3. Download the .stl. Without an account, files are deleted within 24 hours; signed in, they are kept until you delete them.
FormatsWhat you are holding

3D Manufacturing Format file (.3mf)

3MF was designed to replace STL for 3D printing. It records units, colour and material, keeps multiple objects separate, and is compressed. Bambu Studio, PrusaSlicer, Cura and Windows all read it. The shape is still a triangle mesh.

You are printing and want units, colour and part structure to survive the handover.

STL file (stereolithography) (.stl)

STL is the lingua franca of 3D printing: a flat list of triangles. No unit, colour, material or history — a cylinder is a fan of flat strips. The missing unit is the classic cause of scale accidents. Every slicer and mesh tool reads it.

You are printing, meshing or sending to a bureau — where triangles are what is wanted.

Questions10 answered
Does it work with a Bambu Studio or OrcaSlicer project 3MF?
Yes. Those files keep each object's mesh in its own part of the package, and every part is read. Print settings and plate layout are slicer data, not shape, and are not carried.
Why convert 3MF to STL at all?
Because something downstream asks for STL: an older slicer, a print service's upload form, or a mesh tool. When the slicer takes 3MF, keep the 3MF; it records the unit and keeps objects apart.
Do colours survive?
No. STL stores triangles and nothing else, so colour, paint and material are lost. OBJ or GLB are the formats here that can carry appearance.
My 3MF has several objects. Do I get several STLs?
No, one STL holding all of them, each where the 3MF placed it. To print one alone, delete the others in the slicer or export that object by itself.
Is the 3MF to STL converter free?
Yes. 5 conversions a day with no account and no card. A free account raises the limit and adds 25 credits. Choose In your browser instead and there is no daily limit at all.
Does anything change in the geometry?
A direct mesh conversion: the triangles are rewritten, not rebuilt. The shape is unchanged — same triangles, same dimensions. Only the container changes.
Will the STL file be the right size?
It is written in millimetres. STL records no unit, so choose millimetres if your slicer asks. 3MF records units in the file.
How big a file can I convert?
To a mesh format like STL: 300 MB with a free account, 200 MB without one. To STEP, Parasolid or SLDPRT: 140 MB, because rebuilding a solid takes about twice the memory of writing a mesh. Maker and Studio convert up to 830 MB and 380 MB — a large conversion on a paid plan gets the server to itself.
Is it safe to upload my 3MF file?
Files travel encrypted and are processed by machine on our own servers — no third parties, no ads or trackers, no AI training. Or skip the upload: choose In your browser above the drop zone and this conversion runs on your own device, so the file never leaves it.
Is my 3MF file deleted after converting?
Without an account, the upload and the result are deleted within 24 hours. With an account, both stay in your files until you delete them; deleted files leave our servers within 24 hours.
Beyond convertingSame file, four workspaces

Keep the part open: fill it with a lattice, check it with FEA, texture a surface, or slice it into cut-ready sheets. These workspaces are in early access — create an account, then apply from inside the app.

Create free account See pricing

ReadWhy this works the way it does
AlsoOther ways in
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Going the other way? Convert STL to 3MF.