Free STEP to STL converter
STP to STL for 3D printing

Drop a STEP or STP file from SolidWorks, Fusion 360, Inventor, Onshape or FreeCAD and save it as STL for your slicer, with the size and a watertight check shown before you download.

The conversion runs in your browser, so the CAD file never leaves your computer.

Drop a STEP file here or choose a file. STEP (.step, .stp) and IGES (.igs, .iges) from any CAD program. OBJ, FBX, IFC and other 3D files work too.

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Free, no sign-up. Your file stays on your computer. It is opened and converted in this browser tab and is never uploaded to us or anyone else.

STEP, STP, IGES and IGS to STL
Size and a watertight check before download
Binary or ASCII STL, or OBJ and GLB

How it works

How to convert STEP to STL

3 steps, and the CAD file never leaves your computer.

1. Export STEP from your CAD program

SolidWorks, Inventor and Fusion 360 files cannot be read outside their own software, so save a STEP copy first (the menu steps are below). Then drop the .step or .stp file here.

2. Check the part

The model opens in 3D with its size in millimetres and whether it is made of closed solids, which is what a slicer needs. The STEP viewer also shows volume and printed weight.

3. Download the STL

Binary STL is the smallest and what Cura, PrusaSlicer, Bambu Studio and OrcaSlicer expect. Choose ASCII STL only if another program asks for it.

Export STEP

How to export STEP from SolidWorks, Fusion 360, Inventor and more

Native CAD files cannot be read outside their program. Their STEP export can.

SolidWorks

File > Save As, then STEP AP214 (*.step). An .sldprt or .sldasm file cannot be opened by any free converter, so this step comes first.

Fusion 360 and Onshape

Fusion 360: File > Export, then STEP. Onshape: right-click the Part Studio tab, Export, and choose STEP.

Inventor and CATIA

Inventor: File > Export > CAD Format, then STEP. CATIA: File > Save As and choose stp as the type.

FreeCAD and Rhino

FreeCAD: select the body, File > Export, STEP with colors. Rhino: File > Export Selected and choose STEP.

Before you print

What changes when STEP becomes STL

Facets, assemblies and units.

Curved faces become facets

STEP stores exact curves; STL stores only triangles. Curves are cut into fine facets that print smooth at normal layer heights. There is no quality setting.

Assemblies and parts

An assembly comes through as one STL with every part in place. The watertight check looks at each part on its own, so an assembly of closed parts passes. To see the parts one by one, open the file in the STEP viewer.

Units

STEP files carry their units, and the STL is written in millimetres, which every slicer assumes. The size shown before download is the size it will print.

STL back to STEP

Going the other way, STL to STEP, is possible in the 3D converter, but the STEP will be made of facets, not exact surfaces, and a CAD program cannot edit it like the original.

From CAD file to images

What we make from STEP files

Product designers and manufacturers send us their CAD files to be turned into images that sell the product before the first one is made.

3D product rendering

Photoreal studio and lifestyle images of your product, made directly from the STEP file.

See product rendering

3D modeling

Clean models built from drawings, sketches or a rough mesh, when there is no CAD file yet.

See 3D modeling

Architectural visualization

Photoreal images of buildings and interiors, with your product placed in them.

See architectural visualization

STEP to STL FAQ

Questions about converting STEP to STL

File types, quality, assemblies and units.

Ask us a question

Is STP the same as STEP?

Yes. .stp and .step are the same format, ISO 10303, and both open here. IGES files (.igs, .iges), an older exchange format, open too.

Can I convert SLDPRT, IPT or F3D files to STL?

Not directly: these are closed native formats that only SolidWorks, Inventor and Fusion 360 can read. Save a STEP copy from the program first, then convert that here. The menu steps are on this page.

Will the STL be accurate enough to print?

Yes for 3D printing. The curves are cut into fine facets, far smaller than a printer's layer height, so the print looks smooth. For machining, use the STEP file itself, not an STL.

Why does it say a part is not watertight?

Some STEP files contain open surfaces instead of closed solids, for example a surface body or a part exported with missing faces. A slicer may fail on those. Close the body in your CAD program and export again.

Is my CAD file uploaded?

No. The file is opened and converted in this browser tab on your own computer and is never sent to us or anyone else. It is free, with no sign-up.

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