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Understanding Step Files

Engineering and 3D model design have over time depended significantly on standardized solutions, including how to share and collaborate on complex three dimensional model data. There is no denying that the STEP (Standard for the Exchange of Product model data) file has been a core format in the strengthening of this convergence.

This guide analyses all that applies to step files. It covers the importance, history, and applications of this file type. The pros and cons of STP files have also been outlined. Read on for more on this file format that is more established than most people think.

What is a Step File?

What is step file

To start with step file definition, STEP stands for “Standard for the Exchange of Product model data.” It is a popular and acceptable file format in the fields of engineering and 3D computer aided design (CAD). These fields use the stp file extension to ensure the seamless flow of 3D models and their related information from one CAD software to another.

Step files are significant in several things, but the most notable is the summation of dimensions, properties, and other aspects of the 3D model. The ISO technical committee suggests standards that make STEP files capable of cross-platform compatibility with nearly every CAD program.

STP and STEP files are often used interchangeably. While they are largely the same in terms of format, their file extensions are different.

Users value the STP file extension for its international recognition and other strengths. Being globally renowned makes it easy for different computer aided design CAD systems to support it.

Here is a summary of the advantages and features of stp files:

  • Independent of any platform – support different software programs for CAD file

  • Neutral, meaning that it is not tied to any vendor

  • Versatile, supporting a wide range of 3D models, from small components to large assemblies

  • Consistent, being a product of the ISO (International Organization for Standardization)

  • Comprehensive – They represent 3D models plus their metadata such as tolerances, dimensions, and properties.

  • Defined by the file extensions .step or .stp.

Building such a revolutionary file format was not a one-day exercise, as the history of this popular file format shows.

History of the STEP

Step files

After the formation of the Initial Graphics Exchange Specification (IGES) in the 1970s, there was a need for even more part geometry and 3D data. Consequently, the International Standards Organization (ISO) decided to build upon the IGES by creating the Standard for the Exchange of Product Data (STEP) file in the 1980s. However, the step file would only be extensively released in the 1990s.

Over the decades to date, there have been numerous revisions of the step file. While the first edition of this file format was released in 1994, there were other versions in 2002 and 2016.

In the 2002 edition, some data sections had extension and corrigendum additions. The 2016 edition, which was the third one, saw the addition of reference and anchor sections. These would allow the use of external references for the storage of entities and values.

We expect to see even more improvements to the STP files in the future.

How to Open a STEP File?

When you want to use the STEP file or any other file, the first question would be how to open it. You need software to open the .STP file. A STEP file can be opened in various CAD programs. However, programs that run on Windows tend to be the simplest to navigate. Overall, the process of opening a STEP file is easy on most of these platforms.

Popular software programs to open and view stp files include AutoCAD, SolidWorks, Onshape, and Catia.

First, find the location of the stp files in the computer. If the step file is within a folder, open the folder. Then, right-click on the STEP file and choose Open. You could also double-click or select File > Open.

If your computer has computer aided design CAD software, you should be able to see the step files within it. Click on the program to automatically open the STP file.

Here is a summary of the advantages and features of stp files:

  • Open STP File Format Online

    You could also opt to open the STP file online, but this depends on whether the right software or tools are available. For instance, you need access to an online STP viewer.

How to Create and Edit a STEP file?

Given the importance of 3D models in digital design tasks, the capability to create and edit a step file is equally necessary for the user.

Once you have the necessary CAD software, follow these steps:

All the 3D elements in a STEP file are in one area so it is relatively easy to create the file and make any edits. This capability makes a lot of sense in instances where STP files are prevalent, for instance, in 3D printing and CNC Machining.

Now, when considering to creating and editing a step file, the first step is to ensure you have the right CAD software. You want to choose the CAD systems that most suit your project needs, i.e. support the same file format. This refers to CAD programs that are used extensively – SolidWorks, Autodesk Fusion 360, PTC Creo, and so forth.

This is an important step in creating and editing step files because it removes the likelihood of compatibility issues arising. Because there are usually several versions of a program, it is important to ensure your CAD software is up to date. Once you have the necessary CAD software, follow these steps:

  • Open the CAD software

  • Access the STP file through the software.

  • Use the viewing tools in the software to navigate through the step file

  • Using the available editing tools, make the desired changes to the file.

  • Finally, save the STP file using the formats STL, STEP, or whatever extension is available.

How to Create/Convert Step File Formats?

In the course of the project, you may want to create or convert step files to other formats such as ACIS (Geometric Modeling Kernel), STL file, and IGES. The reverse process is also possible i.e. converting from other formats to step files.

Various tools are available (both offline and online) to facilitate such file creation and conversions. Follow the following steps to create a step file:

  • Open the CAD platform

  • Start a project on the tool and create a 3d model

  • You may also import the model if already available elsewhere

  • Check the model for accuracy and other details

  • Go to the save or export option and ensure the availability of the file extension

  • Choose the file name and location, then save

It may also be necessary to convert step files. Typically, the file type is converted to an STL file.

  • To convert step files:

Open the STEP file

Convert a step file by clicking Save as STL or Export to STL

Editing the Step File

When the client asks for modifications or you wish to experiment with the design, editing the step file becomes necessary. How do you go about it?

First, launch the CAD program to open the STP file. Go to the “File” menu and select “Open”. Go to where you stored the STP file and double-click on it.

The CAD software will open the STP file as it does to other CAD files in a suitable format that can be used in this environment. Once the file is open, you can edit it anyhow you want using the editing tools provided. For instance, in AUTOCAD, you can use editing tools such as Move, Rotate, Mirror, and Trim.

Pros and Cons of Step File


Here is a rundown of the pros and cons of step files.

The Pros of Step File

  • Use in Multiple Industries

The biggest advantage of the step file format is that it is acceptable across different industries. As we have already mentioned, this format is compatible with a range of software programs including ArchiCAD, SolidWorks, and Autodesk Fusion. These options have the opening and editing tools needed to handle the files.

  • Applicable in Varied Projects

Also advantageous is that the step files support numerous design projects. For instance, you can use the step or STP file for your 3d models, transfer designs, validate designs, and so on. Since the step files work well with different cad programs, editing and sharing design tasks is possible, even on different devices.

  • Saves Entire Project Body

Regarding saving data, the applicability of the non-uniform rational basis spline (NURBS) is a big plus. Thanks to this, customization and editing work even after the model has been exported. This file format saves the entire body of a project.

  • Supports Intricate Design Projects

Considering the use of 3d data modeling language, it is understandable why step file formats can save the intricate details of a design.

The Cons of Step File

  • Storage Inefficiency

One of those is the fact that the step files are not that storage efficient. In other words, these files tend to demand more storage space compared to other common file format options.

  • No History and Intelligent Parameters

The step files also lack history and intelligent parameters. Unlike some other popular file options, step files cannot save elements such as the material and texture of a model. The reason is that the STP file is designed to disregard such model data on saving.

What is the Difference Between a STEP vs OBJ vs IGES vs STL File?

You cannot talk about STEP files and the exportation of 3D models and disregard other file formats. Other popular file formats for the handling of 3d models are OBJJ, IGES, and STL files.

STL (Stereolithography)

STL files have become common in recent years, particularly due to their relevance in the 3D printing industry. The file uses triangular facets to represent 3D models. Simple, highly compatible, and Open, this file is extremely popular.

However, being based on the storage of objects with triangular appearances makes STL files relatively inaccurate. In 3D printing, these triangular meshes are not a big issue provided the inaccuracies are less than the 3D printer’s resolution. The lack of texture and color data is also a limitation.

IGES (Initial Graphics Exchange Specification)

Before STEP files, there was the IGES (Initial Graphics Exchange Specification), a file format renowned for its capability to encode curves. This allows the file to remain accurate in the exportation process. However, an accurate file does not mean perfection. For instance, the IGES file makes splines polylines.

OBJ Files

Initially meant for animations, the OBJ file is also popular for 3D models. OBJ files are synonymous with polygonal faces. This allows them to have a closer representation of the model geometry, particularly when compared to STL files.

Notable Difference in Details and Accuracy

The difference between these file systems adds up to the level of accuracy in the storage of 3D models. These file formats record model geometries and other elements differently.

OBJ and STL files have excellent approximation qualities that support 3D printing. STEP and IGES files are perfect for CNC machining applications.

Comparing the four file formats, the STEP files come out tops as the best in accurate file sharing and details. For instance, if you consider STL files, the focus is only on the model’s exterior geometry. However, the step format saves the complete body of the model.

Considering this comparison and if you are not sure which file to use, we would recommend STL files in 3D models and STEP files for the rest of the manufacturing methods.



With this coverage of the basics of step files, you now have important information regarding how and where to use the file type. We have gone over the details of the content of step files, the history of step files, how to open a step file, and how the file extension compares to others.

What this post reiterates is that STEP files are popular within the manufacturing industry for their compatibility with leading CAD software, among other benefits. Still, you need to weigh all the details of your project to determine if the capabilities of this file match the requirements.


Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.