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.stepSTEP→.3mf3MFtessellated

Convert STEP to 3MF

Convert STEP to 3MF in your browser. The conversion runs on this page and the file never leaves your computer.

Drop your .step file

up to 250 MB · .step .stp

Free, and it opens in this tab. Nothing is uploaded, and there's no account to make.

Runs locally · nothing uploaded · the CAD kernel loads once you choose a file

Before you convert: what this keeps and what it destroys

Preserved

  • The shape, to within the tessellation tolerance
  • Overall dimensions and proportions
  • Watertightness, where the input is watertight
  • The unit, recorded in the file
  • Colour
  • Separate parts and their positions

Destroyed

  • Exact curves and surfaces, replaced by triangles
  • The feature tree and any parametric history

↺ the reverse: 3MF → STEP · about .step · about .3mf · just view it instead

Why people convert STEP to 3MF

The right conversion for 3D printing a CAD part, if your slicer accepts 3MF. Every current one does.

Compared with going to STL, you keep the unit, so there's no ambiguity about scale. You also keep the assembly structure if the STEP had one, so a multi-part model lands on the plate as separate parts instead of one merged body. The file is also a good deal smaller.

The exact surfaces still become triangles, which is unavoidable when the destination is a mesh format. Check that curved faces are smooth enough at your print size before you commit to a long print.

What you get

You get a binary 3MF file containing triangles. The reader tessellates supported surfaces or uses saved render meshes where required by the source format. Inspect curved faces at the intended output size. The triangle count depends on the model and the reader's meshing settings.

Carried across: the unit, recorded in the file, supported base or vertex colour, the supported part structure.

The conversion runs in your browser. Your file stays on your computer and is not uploaded.

What to check afterwards

  • STEP declares its unit in the file. Check the output dimensions in the receiving application, especially when its import settings can override the unit.
  • Curves become facets. STEP stores exact surfaces, so a hole is a cylinder with a radius. 3MF stores triangles, so that cylinder becomes a many-sided prism. Look at curved faces in the result at the size you intend to make the part.

If you need something this conversion cannot give you

If you need editable CAD geometry, don't convert at all. Open the STEP file directly in FreeCAD, Fusion, Onshape or SolidWorks. Every mesh format destroys the exact surfaces, and no later conversion brings them back.

Going the other way

Convert 3MF back to STEP exists, but it is not the inverse of this page. Going this way tessellates exact surfaces into triangles. Going back rebuilds a faceted solid out of those triangles. You do not get your original surfaces back, and the round trip is lossy in a way that compounds.

How we know this conversion works

This pair was checked against 44 files from the test corpus on 2026-09-04. Each run parses its own output back in and compares the bounding box, the triangle count and, for closed solids, the volume against the input.

A pair that fails those checks doesn't get a page. That's why this site lists 120 conversions and not the several hundred a format-times-format grid would suggest.