STL 3D Model (.STL)
STL (Stereolithography) is a 3D model format that represents surfaces as a collection of unstructured triangular facets, each defined by a unit normal vector and three vertices. Originally developed by 3D Systems for stereolithography 3D printing in 1987, it stores only geometry with no color, texture, or material information. STL exists in both ASCII and binary variants, with binary being more compact.
Advantages of STL 3D Model
What the STL format does well, and why you might choose it.
- Universal standard format for 3D printing accepted by all slicers and printers
- Extremely simple format that is easy to generate and parse
- Supported by virtually all 3D modeling and CAD software
Limitations of STL 3D Model
What the STLformat doesn't do well, and when to choose another format.
- No support for color, texture, materials, or any non-geometry data
- Stores only disconnected triangles with no topology or vertex sharing information
- ASCII variant produces very large files; binary is more efficient but still lacks compression
What STL files are used for
- 3D printing file preparation and slicer input
- Rapid prototyping and additive manufacturing
- Simple 3D geometry exchange between CAD and modeling tools
Convert to STL
The most common formats people convert to STL, ready to convert in seconds.
Convert STL to other formats
Convert STL 3D Model files into the format you actually need.
Frequently asked questions about STL
What is a .STL file?
STL (Stereolithography) is a 3D model format that represents surfaces as a collection of unstructured triangular facets, each defined by a unit normal vector and three vertices. Originally developed by 3D Systems for stereolithography 3D printing in 1987, it stores only geometry with no color, texture, or material information. STL exists in both ASCII and binary variants, with binary being more compact.
What is the MIME type of STL?
The official MIME type for STL files is application/sla. This is the value web servers and applications use to identify the format when transferring files.
What category does STL belong to?
STL is a 3D Model Converter format. Files in this category share common conversion paths and use cases.
How do I open a .STL file?
STL files are typically opened by software that natively supports the STL 3D Modelformat. If you don't have a compatible application, the most reliable approach is to convert the file to a more universal format using the converters listed above. Most STL 3D Model files convert to widely-supported alternatives in seconds.
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