Convert STEP to STL (Free)
Also converts OBJ, GLB, PLY, USDZ, 3MF, WRL from the same file.
Runs in your browser. No upload, no signup, nothing to install.
Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.
How to convert STEP to STL
- 1
Open your .step file
Drag it onto the viewer above, or click "Open a STEP File". Files up to 200 MB open directly; the parse runs in a worker so the page stays responsive.
- 2
Pick Stereolithography in the Export menu
Click Export in the toolbar, then STL (.stl).
- 3
Download
The .stl is written in the browser and saved straight to your downloads folder. No queue, no email, no watermark.
What survives the conversion
A file conversion is a translation, and formats do not carry the same things. Here is exactly what moves from STEP into STL, and what does not.
| Geometry | Reduced | STEP stores exact B-rep solids and STL stores triangles, so the surfaces are tessellated. Curved faces become faceted at the display tolerance, which is fine for visualization, printing and clash checking, but not for further parametric CAD work. |
|---|---|---|
| Colors and materials | Dropped | STL has no concept of color or materials, so the material colors in your STEP file are not written. The geometry is unaffected. |
| Layers and structure | Dropped | STL is a single flat body with no layers or named parts. Everything merges into one object. If you need the structure, export to GLB, OBJ, DXF instead. |
| Units and scale | Dropped | STL stores no unit. Coordinates are written in meters, so set the import unit to meters if the destination asks. |
What the STL writer emits: Binary STL, one triangle record per face, positions written verbatim in meters.
The source: STEP (ISO 10303) (.step, .stp)
The B-rep solids and surfaces of the assembly, tessellated to display meshes, with the product tree and real units.
The target: Stereolithography (.stl)
The universal 3-D printing mesh. Every slicer and every printing service takes it.
Opens in: Cura, PrusaSlicer, Bambu Studio, Meshmixer, any printing service.
Your file never leaves your computer
Both the STEP parser and the STL writer are JavaScript and WebAssembly running in your own browser tab. There is no upload step, no server-side conversion queue, and no copy of your file anywhere but your machine. That matters for drawings under NDA, for client work, and for anything you would not email to a stranger.
Frequently asked questions
▶Is this STEP to STL converter free?
Yes. No signup, no watermark, no per-file limit and no paid tier. Innerscene.
▶Is my STEP file uploaded anywhere?
No. The file is read with the browser file API and converted in the same tab. Nothing is sent to a server unless you explicitly click Share, which is a separate, opt-in feature.
▶Will my colors and materials survive the STL export?
STL has no concept of color or materials, so the material colors in your STEP file are not written. The geometry is unaffected.
▶Do layers and named parts carry into the STL file?
STL is a single flat body with no layers or named parts. Everything merges into one object. If you need the structure, export to GLB, OBJ, DXF instead.
▶Will the STL open at the right size?
STL stores no unit. Coordinates are written in meters, so set the import unit to meters if the destination asks.
▶How large a STEP file can I convert?
Up to 200 MB, and the ceiling adapts to how much memory your device reports. The conversion runs on your own hardware, so a desktop with plenty of RAM will handle more than a phone.
▶Can I convert STL back to STEP?
Yes, the other direction works too. Bear in mind that anything the first conversion dropped is not restored by converting back. STL → STEP
▶Which browsers does it work in?
Chrome, Edge, Firefox and Safari, on Windows, macOS, Linux, iOS and Android. No plugin and no extension.
Convert STEP to something else
Convert something else to STL
Or start from the universal 3D viewer.