File Format

What Is an STL File?

STL (STereoLithography) has been the 3D printing standard since 1987. It stores nothing but a raw list of triangles — no color, no units, no materials — which is exactly why every slicer (Bambu Studio, PrusaSlicer, Cura) accepts it without question. If your file needs to go from a screen to a printer, it's almost always going to pass through STL at some point.

What STL can and can't store

YESTriangulated geometry. That's the entire format — a mesh reduced to a flat list of triangles.
NOColor or texture. STL has no field for it — physically cannot represent color, even on multi-color printers.
NOUV coordinates or materials. No texture mapping, no material references at all.
NOAnimation. STL describes one static shape, nothing that moves.
YESSingle file.Since there's nothing else to store, one .stl file is always complete on its own.

Common problems with STL files

COMMONColor and texture are gone for good. AI-generated models (Meshy, Tripo, Hunyuan) usually come with vertex colors or a texture map — exporting to STL discards all of it, since the format has nowhere to put it.
COMMONCurves become faceted. STL only stores flat triangles, so smoothly curved surfaces get approximated into visible facets — more noticeable the fewer triangles a model has.
HONESTNon-manifold edges and holes. Because STL is just a triangle soup with no higher-level structure, gaps and non-manifold edges are easy to introduce and slicers often reject them outright. Our free STL repair tool fixes exactly this.

Convert STL to another format

GLB to STL OBJ to STL STL to OBJ

Got a broken STL, GLB or OBJ file?

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Deep repair (keeps colors)20 credits

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