Windows
Compatible applications
Quick Facts
Basic information about this file format
Extension
.STL (.STL)
File Type
Stereolithography
Category
Data
Best first step
Use compatible software
Quick Summary
A practical overview of the .stl (.stl) file format
STL (Stereolithography) is a file format native to the stereolithography CAD software created by 3D Systems. STL files describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes. It represents the surface as a c…
File extension
.STL (.STL)
File type
Stereolithography
Category
Data
Recommended action
Open with a trusted compatible app
How to open a .stl (.stl) file
Start with a trusted app that supports this format
- Check the file extension carefully and confirm that the file name really ends with .stl (.stl).
- Use software that supports this file type. If one app does not work, try another compatible program for the same platform.
- Update the application if the file was created by a newer version of the software.
- Scan files from unknown sources before opening them, especially documents, archives, scripts, installers, and executable files.
What is a .stl (.stl) file?
File extension details and usage information
STL (Stereolithography) is a file format native to the stereolithography CAD software created by 3D Systems. STL files describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes. It represents the surface as a collection of triangles, also known as a mesh. Each triangle is defined by the coordinates of its three vertices and a normal vector indicating the triangle's orientation. Because STL files only describe the surface geometry, they are widely used for rapid prototyping, 3D printing, and computer-aided manufacturing (CAM). The simplicity of the format makes it easy to process and manipulate, allowing for efficient slicing and toolpath generation. STL files are commonly used to transfer 3D models between different software packages and manufacturing equipment. The format is widely supported by 3D modeling software, slicing software, and 3D printers, making it a standard for representing 3D models for additive manufacturing processes. While STL is widely used, it has limitations, such as the lack of support for color, texture, and material properties. This has led to the development of alternative formats that offer more comprehensive model representation.
Software Compatibility
Programs that may open or work with .stl (.stl) files
macOS
Compatible applications
Linux
Compatible applications
Mobile
Mobile applications
Can .stl (.stl) files be converted?
Options for saving or exporting this file to another format
In many cases, a .stl (.stl) file can be converted by opening it in compatible software and using an option such as Save As, Export, or Convert. The available output formats depend on the file type and the application used.
- Use the original software that created the file when possible.
- Check whether the application supports exporting to common formats.
- Be careful with online converters when working with private, business, or sensitive files.
- If conversion fails, the file may be corrupted, incomplete, encrypted, or not actually a .stl (.stl) file.
Why can't I open a .stl (.stl) file?
Common reasons this file type may not open correctly
Wrong software
The file may require a specific program that supports the .stl (.stl) format.
Incorrect extension
The file extension may have been renamed manually, even though the actual file format is different.
Corrupted file
The file may be incomplete, damaged during download, or transferred incorrectly.
Outdated app
Your software may need to be updated before it can open newer versions of this file format.
Frequently Asked Questions
Common questions about .stl (.stl) files
To open a .stl (.stl) file, use software that supports this file format.
- MeshLab
- Blender
- FreeCAD
- Autodesk Fusion 360
- SolidWorks
Open the file in compatible software and look for options such as Save As, Export, or Convert. If no export option is available, the file may require a specialized converter or the original application that created it.
- Verify that the file extension is correct.
- Install or update compatible software.
- Try another application that supports this format.
- Check whether the file is corrupted, incomplete, or encrypted.
A file extension alone does not guarantee whether a file is safe or unsafe. Only open files from trusted sources, scan unknown files before opening them, and be especially careful with executable, script, archive, and document files.
File safety tips
Use caution with unknown files
Only open files from trusted sources. Before opening a .stl (.stl) file, scan it with antivirus software, verify that the file extension is expected, and avoid running unknown executable, installer, macro-enabled document, or script files.