3D printing and making
Convert a STEP file to STL for 3D printing
CAD programs save STEP files; slicers want STL or 3MF. Convert in your browser, check the part in 3D, and print.
STEP to STLFree · No sign-up · Files stay on your device
Open STEP to STL
Why convert STEP to STL
STEP holds exact, mathematical surfaces. Slicers like Cura, PrusaSlicer and Bambu Studio need triangles instead, in an STL or 3MF file.
Online converters usually upload your design. Here OpenCascade, the same geometry engine used by FreeCAD, runs in your browser, so unreleased designs stay private.
When you might need this
- Parts from suppliersManufacturers share STEP models of their parts and enclosures.
- Your own designsFusion, Onshape, SolidWorks or FreeCAD exports, ready to print.
- Download sitesModels from GrabCAD and similar sites, often only offered as STEP.
Key benefits
- Exact sizeMillimetres in, millimetres out: a 10 mm cube stays 10 mm.
- Smoothness you chooseMore triangles for smooth curves, or fewer for a lighter file.
- See it firstTurn and zoom the part before saving.
How to convert
- Open your .step or .stp file in STEP to STL.
- Choose how smooth curved surfaces should be (Normal suits most prints).
- Choose STL, or 3MF for modern slicers.
- Press Convert, check the part in the preview, and save.
Tips
- 3MF files are smaller and always state their units, which avoids size mix-ups.
- Assemblies come out as one file holding every part; separate them in your slicer if needed.
- For holes and fine threads, choose Smoother.
STEP to STLFree · No sign-up · Files stay on your device
Open STEP to STL
Questions
Can I convert STL back to STEP?
Not usefully: an STL has only triangles, so the result would be a STEP made of thousands of flat faces, not editable surfaces.
My part came out tiny or huge.
STEP to STL keeps millimetres. If the design was made in inches, choose "Inches to millimetres" under Size.
Is my design uploaded?
No. The STEP file is read and converted inside your browser.
Tools for this job
More guides
- 3D printing and makingMake a 3D printed sign from your logoTurn a logo or SVG design into a raised 3D model on a base plate, ready to print as a sign, badge, keyring or stamp. Choose the size and height.
- 3D printing and makingMake a lithophane from a photoTurn any photo into a lithophane STL: a 3D print that shows the picture when light shines through it. Settings that print well, explained.