STL File Format

STL 3D Model category

STL is the workhorse format of 3D printing: a plain list of triangles describing the model surface, understood by every slicer and CAD tool.

Typical use: STL is what 3D printers and slicing software (Cura, PrusaSlicer) expect — the final step before printing.

About the STL format

STL (STereoLithography, 3D Systems, 1987) is the format 3D printing was built on. It stores exactly one thing: a mesh of triangles with normal vectors — no color, no texture, no units, no hierarchy. Slicers assume millimeters and treat the surface as the whole truth, which is all a printer ever needs.

That minimalism cuts both ways. Every slicer and CAD tool on earth reads STL, and files are simple to repair and check (watertightness, manifold edges). But smooth curved surfaces need thousands of triangles, so STL files bloat quickly, and any appearance data is lost the moment you convert to it.

Strengths

✓ Universal in 3D printing — every slicer reads it
✓ Dead-simple geometry, easy to validate and repair
✓ Binary variant is compact for its content

Limitations

✗ No color, materials or texture whatsoever
✗ No units — slicers assume millimeters
✗ Curved surfaces need huge triangle counts

Structure: Triangle mesh only
Materials: None
Compatibility: All slicers and CAD
Best for: 3D printing

Convert STL to…

4 direct directions plus 19 workflows, sorted A–Z; 🔥 marks popular targets.

STL to GLB Hot STL to glTF STL to OBJ Hot STL to PLY

Cross-engine workflows

STL to 7Z STL to APK STL to JAR STL to JFIF STL to JPE STL to JPEG STL to JPG STL to PNG STL to PNG24 STL to PNG8 STL to TAR STL to TAR.BZ2 STL to TAR.GZ STL to TAR.XZ STL to TBZ2 STL to TGZ STL to TXZ STL to WIM STL to ZIP

Convert other files to STL…

3DS to STL 3MF to STL DAE to STL FBX to STL GLB to STL Hot glTF to STL LWO to STL MD2 to STL OBJ to STL Hot PLY to STL VRML to STL

Frequently asked questions

What is a STL file?

STL is the workhorse format of 3D printing: a plain list of triangles describing the model surface, understood by every slicer and CAD tool.

How do I convert STL files online?

Pick a target format from the "Convert STL to…" list below, drop your file and hit convert. Everything runs in your browser — no install, no upload, no watermark, no limits.

Is it safe to convert STL files here?

Yes. Every conversion is performed by your own device inside the browser — files never leave for a server, and the page keeps working even offline.

Which formats can STL convert to?

This page lists all 23 directions across documents, images, audio, video, spreadsheets and archives — each one is its own free converter page.