Will the STEP have real curves?

No. An STL stores only triangles, so a round hole comes out as a many-sided one. Flat areas do become single faces, which is what you need to measure the part, cut into it or sketch on a face. For true curves the part has to be modelled again, and Voloom can do that from a description or a photo.

Can I edit the STEP in Fusion or SolidWorks?

Yes, as a solid body: cut it, extrude from its flat faces, add holes, and fillet its straight edges. It has no feature history, so there are no sizes to change. For that, rebuild it as a parametric part in Voloom.

Why is my mesh too big to convert?

Each triangle becomes a CAD face, and past 100,000 the file gets too big for most CAD programs to open comfortably. Reduce the triangle count in Blender (Decimate) or Meshmixer first. Brackets and enclosures are usually well under; scans and sculpts are usually over.

Why is the STEP not a closed solid?

The STL has holes or gaps, so its faces cannot close up. The report after converting says whether it closed. Run the STL repair tool first, then convert again.

Is the STL to STEP converter free?

Yes. You get 3 runs a month without an account. Sign in with your email, free, and there is no limit.

No. The file is read and converted in your browser. It never reaches our servers.

What units is the STEP in?

STL: None in the file. Slicers read the numbers as millimeters. STEP: Explicit. Usually millimeters. The converter does not guess. Use the scale option if the size looks wrong.

How do I open a STEP file?

Fusion, SolidWorks, Onshape, FreeCAD, and Inventor all open STEP.

stl to step

Convert STL to STEP

Free STL to STEP converter. Runs in your browser, so the file never leaves your computer. Preview the model, then download the STEP.

Drop STL here, or choose a file

Stays in your browser. Nothing is uploaded.

Choose file

Good to know

No converter can turn triangles back into editable CAD, and most online ones write each triangle as a loose face. This one closes the triangles into a solid and merges every flat area into one face, so a box comes out with six faces you can measure and sketch on in Fusion or SolidWorks. Curves stay faceted: a cylinder is still a polygon. For a real parametric part, describe it to Voloom and it builds the solid from scratch.

How it works

1Drop your STL file in the box above. It is read in your browser.
2Check the preview and the size. If the STL came in meters or inches, set the scale.
3Download the STEP. It opens in Fusion, SolidWorks, and Onshape.

What carries over

Shape: Kept
Colors: Dropped
Materials: Dropped
Units: Dropped
Separate parts: Dropped
Exact curves: Dropped

About STL

STL (Stereolithography). The default 3D printing format since 1987: a bare list of triangles. Every slicer reads it, but it has no units, no color, and no parts.

Units: None in the file. Slicers read the numbers as millimeters. Up axis: Z. Opens in Bambu Studio, PrusaSlicer, Cura, OrcaSlicer, and Blender.

About STEP

STEP (ISO 10303 STEP). The ISO standard for exchanging exact CAD solids. Faces are true curves, not triangles, so another CAD program can edit and dimension them.

Units: Explicit. Usually millimeters. Up axis: Z. Opens in Fusion, SolidWorks, Onshape, FreeCAD, and Inventor.

Questions

Will the STEP have real curves?: No. An STL stores only triangles, so a round hole comes out as a many-sided one. Flat areas do become single faces, which is what you need to measure the part, cut into it or sketch on a face. For true curves the part has to be modelled again, and Voloom can do that from a description or a photo.
Can I edit the STEP in Fusion or SolidWorks?: Yes, as a solid body: cut it, extrude from its flat faces, add holes, and fillet its straight edges. It has no feature history, so there are no sizes to change. For that, rebuild it as a parametric part in Voloom.
Why is my mesh too big to convert?: Each triangle becomes a CAD face, and past 100,000 the file gets too big for most CAD programs to open comfortably. Reduce the triangle count in Blender (Decimate) or Meshmixer first. Brackets and enclosures are usually well under; scans and sculpts are usually over.
Why is the STEP not a closed solid?: The STL has holes or gaps, so its faces cannot close up. The report after converting says whether it closed. Run the STL repair tool first, then convert again.
Is the STL to STEP converter free?: Yes. You get 3 runs a month without an account. Sign in with your email, free, and there is no limit.
Is my file uploaded?: No. The file is read and converted in your browser. It never reaches our servers.
Will the STEP keep colors and materials?: Where the STL has them, yes.
What units is the STEP in?: STL: None in the file. Slicers read the numbers as millimeters. STEP: Explicit. Usually millimeters. The converter does not guess. Use the scale option if the size looks wrong.
How do I open a STEP file?: Fusion, SolidWorks, Onshape, FreeCAD, and Inventor all open STEP.

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