Convert STL
to 3MF.

Updated 2026-10-19

To convert STL (.stl) to 3MF (.3mf), drop the file below and download the result, in the browser with nothing installed. A direct mesh conversion: the triangles are rewritten, not rebuilt.

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 STL file.stl · 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: 3MF records units explicitly, so the part cannot arrive at the wrong scale.

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

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.

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.

Questions5 answered
Is the STL to 3MF 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: 3MF records units explicitly, so the part cannot arrive at the wrong scale.
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 STL 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 STL 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
MoreRelated conversions

Going the other way? Convert 3MF to STL.