What is a .STL file format? STL Files Explained

November 9th, 2022
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STL is a common technical term in the world of tech, especially in the computer-aided design (CAD) and 3D printing space. STL files or (.stl) file endings are a type of 3D CAD file format. There are many different 3D CAD file formats ranging from the open step and stl formats, to proprietary formats used in Solidworks or Autodesk software.

What is an STL File?

When industries make prototype designs in their Computer-Aided Design software, they must conform to a certain format in which the files are to be saved and transferred. This format has to be an industry standard, and for the designs of prototypes, STL is the one that the industry has unanimously adopted. STL stands for Stereolithography (or Standard Tessellation Language), and is primarily used in Computer Aided Manufacturing (CAM) and 3D printing.

Each surface of a design or model is typically approximated using some combination of triangles; with enough triangles, virtually any complex structure can be constructed and saved in an STL file. STL files can come in both a human-readable ASCII format or a smaller binary file format.

How Do You Open an STL File?

Your options are plentiful when choosing an STL file opener/editor. Some of these will be a personal preference for you, while others are better options for all your editing needs, so let's get on the list!


The Jinolo web-based viewer natively supports stl files. It not only allows designers to open and view files, it also has many collaborative features in the cloud that allows users designers and engineers to comment, inspect and share their designs with a single click. The Jinolo platform is completely in the browser which means that users do not need to install any extra software or plugins to start using the 3D viewer. Start using Jinolo for free!


FreeCAD is an example of open-source software and is completely free. Having seen widespread use over many different applications of 3D printing, this is something of a fan favorite among its community, which constantly works to improve its functionality. As for its use, you're able to not only open and edit existing STL files but also create new ones from scratch! These can then be exported in STL format and are one of our go-to recommendations for beginners in the 3D printing industry.


If you follow tech channels that review computer hardware, you may have heard the name 'Blender' come up numerous times, particularly during benchmarks. There's a reason this is an important benchmark for computer hardware as this is another widely known and loved CAD program, and yes, it is compatible with STL files! The only caveat here is that it is not very beginner-friendly, though we believe once you learn its workings, you'll be glad you put in the effort to get the advanced control it allows.


Working with the same basic principle of combining triangles to make approximations of structures, TinkerCAD software allows you to choose primitive shapes and combine them to get your desired structure. Moreover, you have options for formats apart from STL, including OBJ and SVJ, which you may have seen in certain applications.

How Do You Make or Edit an STL File?

Most popular CAD packages such as Solidworks or Autodesk would allow the designer to create a 3D file and export it as an STL file format. Once the design has been created, you'll want to ensure the file has been saved and then proceed with exporting it. At this point, your software will prompt you to select the format of the design you have just created, which is usually a drop-down menu showing you all the options. Choose STL from this list and click on 'export' to the location of your choice.

Pros and Cons of STL Files


  • Well supported: STL is a universal file format supported by almost all 3D printers. That means there is less of a chance that a designer would need to convert their design to a different 3d file format when prototyping on a 3D printer.

  • Smaller: STL files hold less information about the design which generally means it is a smaller file size than other file formats. This can save space when storing the file and make it easier when sending STL files.


  • Less accurate: Because STL files use triangles to represent surfaces, they do not accurately depict curved surfaces and ultimately when the user saves the model to an STL format, some data is lost. The user would need to save the file in another original CAD file formats such as Rhino 3D to preserve that information about the file.

  • Limited information: STL file cannot store metadata about the file such as the author or location, nor does it have good capabilities for storing information about the texture of the prototype. The designer would need to provide the supplier with supplementary information in a PDF or spreadsheet when prototyping the design. To store more information about colors and textures, OBJ files have also become popular.

STL files are a type of file format, primarily used in the additive manufacturing and 3D printing industry. They are a versatile format supported by most 3d printers and are an efficient way to share designs with suppliers when prototyping new products.