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Resources3D Printing DesignSLDPRT to STL: How To Convert SLDPRT to STL Files
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SLDPRT to STL: How To Convert SLDPRT to STL Files

Xomety X
By Team Xometry
April 12, 2024
 10 min read
Mark Osterman, VP of Technical Sales and Pre-Sales Engineering
June 7, 2024
 3 min read

SolidWorks® is a popular computer-aided drawing (CAD) software program. It is one of the oldest 3D CAD software brands and is used by millions of engineers and designers worldwide. SolidWorks® saves its CAD drawings to a proprietary SLDPRT file type, but this file type cannot be used by 3D printers or CNC machinery. For a 3D printer or CNC machine to manufacture a part from the model, it must first be converted to a commonly used file type, such as STL. 

In this guide, we talk you through the steps involved in converting SLDPRT files to STL files. Here is an outline of the steps to follow:

1. Open the SolidWorks® File.

Begin by launching SolidWorks® and opening the .SLDPRT file you wish to convert. This file is a 3D part file created with SolidWorks®, containing detailed information about the geometric and design aspects of the part.

2. In SolidWorks®, Go To 'File' and Select 'Save As.'

With the SLDPRT file open, go to the 'File' menu in the top left corner of SolidWorks®. From the drop-down menu, select 'Save As.' This option allows you to save your current work in a different file format.

3. Choose 'STL' as the File Type From the Drop-Down Menu.

In the 'Save As' dialog box, you'll see a 'Save as type' drop-down menu. Click on it and choose 'STL (*.stl)' as the file type. STL files are widely used in 3D printing and computer-aided manufacturing because of their simplicity in describing the surface geometry of a 3D object.

4. Set the Desired Options for the STL File, Such as Resolution and Units.

Once you've selected STL as the file type, click on the 'Options' button to adjust the resolution and units of your STL file. The resolution determines the level of detail of the STL model, while the units (inches or millimeters) ensure that the model scales correctly in other software or for 3D printing.

5. Adjust These Settings Based on Your Requirements.

Adjust the STL options according to your specific requirements. For instance, a higher resolution will produce a more detailed model but will increase the file size. Choose the settings that best balance detail and file size for your needs.

6. Choose a Location To Save the STL File.

Determine where you want to save the STL file on your computer. It's a good practice to choose a location that's easy to remember and accessible for subsequent steps in your project workflow.

7. Click 'Save' To Export the SLDPRT File as an STL File.

Click 'Save' to convert and export the SLDPRT file as an STL file. SolidWorks® will process the conversion based on the options you've set.

8. Open the STL File Using a 3D Viewer or Slicer Software.

After saving, you can open the STL file with any compatible 3D viewer or slicer software to review the conversion. These tools allow you to inspect the model for accuracy, quality, and readiness for printing or further modification.

9. Validate the Conversion and Review the Model.

It is important to validate the conversion by closely reviewing the model in your chosen software. Ensure that the details, dimensions, and overall geometry meet your expectations and requirements. This step is crucial for identifying and correcting any issues before moving on to printing or further processing.


An SLDPRT file is a 3D part file generated by SolidWorks®, a computer-aided design (CAD) software program widely used in the engineering and design industry. An SLDPRT file contains a detailed 3D design of an individual part or assembly. Each SLDPRT file stores detailed information including: the part's geometry, features, dimensions, material specifications, and surface finish specifications.

Primarily used in mechanical design, aerospace, automotive, and consumer product development, SLDPRT files are crucial for creating accurate 3D models of components. These files facilitate not only the design and prototyping phases but also support the seamless transition to manufacturing. Although native to SolidWorks®, SLDPRT files can be exported to various formats for compatibility with different CAD systems. 

What Is STL?

STL, originally short for stereolithography, is a file format native to the stereolithography CAD software created by 3D Systems. More recently the file format also goes by other names like Standard Triangle Language, Surface Tesselation Language, or Standard Tessellation Language. STL has become the standard file format for 3D printing. The format is used to store information about the 3D models. The geometry and topography are stored as a series of triangular facets creating a mesh, allowing the representation of complex shapes with simple triangular tiles. STL files contain the raw, untextured surface geometry of a 3D object without any color, material, or other properties associated with more complex file types. 

Each triangle in an STL surface mesh is represented by its three corner points (vertices) and a vector normal to the plane of the triangle indicating which direction is toward the exterior of the object. This simplistic representation makes the model easy to slice and prepare for 3D printing.

The simplicity of this format makes it universally accepted across various 3D printing software and hardware control programs, enabling the easy sharing of models between different systems. However, the lack of detail beyond basic geometry can be a limitation for applications requiring precise color, material definition, or texture mapping. As printing technology advances, formats like .OBJ and .3MF, supporting color and texture, become relevant alternatives. 

STL files can be saved as two types — binary or ASCII format. Binary files are more compact and faster to read and write, making them more common than ASCII files, which are larger and take longer to process but are human-readable.

What Are the Other Ways To Convert SLDPRT to STL?

For those who do not have SolidWorks® or prefer an alternative, there are two other ways to convert SLDPRT to STL. eDrawings® is one option. eDrawings® is a free SolidWorks® viewer from Dassault Systèmes that supports viewing various CAD formats and saving them as STL files. This tool is particularly useful for Windows users, as the MacOS version of eDrawings® does not support saving in STL format, only allowing for the export of 2D image formats.

Numerous online platforms also offer free or paid services to convert SLDPRT files to STL. Websites like AnyConv, ConvertCADFiles, and Miconv can be used to upload the SLDPRT file and then download the converted STL file. This method is convenient for users who need a quick conversion without installing additional software.

Why Do We Have To Convert SLDPRT to STL?

SLDPRT files are native to SolidWorks® and store detailed information about a part's geometry as well as the specific SolidWorks® features used to create it. This format is ideal for ongoing projects within SolidWorks®, where maintaining the integrity of design features, sketches, and references is crucial. However, SLDPRT files are not directly compatible with many 3D printing or CAD programs outside the SolidWorks® environment. Additionally, SLDPRT files created in newer versions of SolidWorks® may not be backward compatible with older versions of the software, presenting a challenge for collaboration or accessing files across different versions.

STL files are a more universally accepted format for 3D printing, characterized by their simplicity in storing 3D model geometry as triangular mesh. While STL files cannot retain detailed information about textures, colors, or SolidWorks®-specific features, they are widely supported by a vast range of 3D printing slicer programs and other CAD software. This makes STL files particularly useful for ensuring compatibility across different platforms and for preparing models for 3D printing, where detailed feature information from the original SLDPRT file is not required. For projects demanding textures, colors, or specific details beyond simple geometry, alternative file formats like 3MF or OBJ are used, as they can include comprehensive data alongside geometric information. 

Is Converting STL to STEP Easier Than Converting SLDPRT to STL?

No. Converting STL files to STEP format tends to be more complex than converting SLDPRT files to STL. This complexity is primarily due to the nature of the file formats involved. STL files are mesh-based and represent 3D objects using triangular facets, without storing detailed information about the geometry's original features or relationships. Conversely, STEP files are designed to hold more comprehensive geometric and topological data of 3D objects, supporting precise dimensions, tolerances, and materials. STEP files capture objects with precise geometry, including curves and surfaces, and carry detailed data like color and texture, essential for CAD and manufacturing. When converting from STL to STEP, the challenge lies in interpolating a mesh into a precise solid model, a process that often requires advanced software and can involve significant manual correction to accurately represent the original design intent.

In contrast, converting SLDPRT files, which are SolidWorks® part files containing detailed 3D design data, to STL is relatively straightforward. This process is well-supported by SolidWorks® and other CAD applications, where the user can directly export SLDPRT files to the STL format with simple adjustments for resolution and scale. The conversion from SLDPRT to STL is typically a one-step process aimed at preparing models for 3D printing.

What Is the Importance of SLDPRT to STL Conversion to 3D Printing?

The conversion of SLDPRT files to STL is crucial for 3D printing because STL files are the universally accepted format for most 3D printing software and hardware. This conversion process transforms detailed CAD models into an STL file, which represents the model's surface as a mesh of triangles. Slicer software takes the STL file, slices it into layers, and generates G-code, which contains the printing instructions. The G-code is sent to a 3D printer, which prints the object layer by layer.

The SLDPRT format contains comprehensive design information that is not needed for 3D printing. When a file is converted to STL format, only the geometric data required to print the model is retained. The STL format ensures compatibility across a wide range of 3D printing technologies, preparing them for physical printing. This conversion step is essential in bridging the gap between digital 3D modeling and the physical manufacturing process in 3D printing.


This article presented converting SLDPRT to STL files, explained it, and discussed the various steps to convert. To learn more about SLDPRT and STL files, contact a Xometry representative.

Xometry provides a wide range of manufacturing capabilities, including 3D printing and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.

  1. SolidWorks® is a registered trademark of Dassault Systèmes SolidWorks Corporation
  2. eDrawings® is a registered trademark of Dassault Systèmes SolidWorks® Corporation


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Xomety X
Team Xometry
This article was written by various Xometry contributors. Xometry is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding, urethane casting, and more.