Format Guide
The universal 3D printing format — simple triangle meshes readable by every slicer, CNC system, and mesh tool.
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| Extension | .stl |
|---|---|
| Full name | STereoLithography / Standard Triangle Language |
| Geometry type | Triangle mesh (facets) |
| Variants | ASCII, Binary |
| Open standard | Yes |
| Supports color | No (binary variant has unofficial color extensions) |
| Supports assemblies | No |
| Supports materials | No |
STL (STereoLithography) was developed by 3D Systems in 1987. It represents a 3D surface as a collection of triangular facets — each triangle defined by three vertices and a normal vector. STL comes in two variants: ASCII (human-readable text, larger files) and binary (5–10× smaller). STL stores no color, material, texture, unit, or assembly information — just raw geometry. Despite these limitations, it remains the most universally understood 3D printing format. Every slicer software (PrusaSlicer, Cura, Bambu Studio, Chitubox) accepts STL.
STL is the default export format for 3D printing. All FDM, SLA, SLS, and resin printers accept STL files. The mesh must be watertight (no holes or non-manifold edges) for slicing to work correctly.
Many CAM systems (Mastercam, Fusion 360 CAM, HSMWorks) accept STL as input for generating machining toolpaths from 3D geometry.
Engineers export design drafts as STL for quick desktop printing to check form and fit before committing to expensive CNC or injection molding runs.
Every slicer (PrusaSlicer, Cura, Bambu Studio), all major CAD systems (SolidWorks, Fusion 360, FreeCAD), and all CAM packages. The most universally readable 3D format.
Commonly converted from STEP or IGES (for 3D printing), to 3MF (for better metadata support), to OBJ (for rendering), or to AMF (for multi-material printing).