STL vs. 3MF: Which Format to Choose for a 3D Model?
STL and 3MF are the two most commonly used file formats in 3D printing. The STL format stores only the part’s geometry using triangles, while the 3MF format also stores color, materials, orientation, and print parameters in a single file. Choosing one over the other affects file size, the risk of errors, and the ease of sharing a project. In this comparison, we analyze their differences, advantages, and limitations.
Although each additive manufacturing technology works differently, there is one stage common to all: computer-aided design (CAD). Once the 3D model is complete, it must be exported to a format that the slicer can interpret.
That’s where the options come in: OBJ, STL, PLY, 3MF, and many others. Two clearly dominate in real-world use: the veteran and universal STL, and the newer and much more comprehensive 3MF.
STL vs. 3MF: The Key Differences at a Glance
The table below summarizes the two formats before we examine them in detail:
| Criterion | STL | 3MF |
|---|---|---|
| Year Created | 1987 (3D Systems) | 2015 (3MF Consortium, led by Microsoft) |
| Data Stored | Geometry only (triangle mesh) | Geometry, colors, textures, materials, orientation, supports and print settings |
| Structure | Flat mesh | Compressed file, similar to a .zip file, encoded in XML |
| File Size | Large for high-accuracy models | Considerably smaller |
| Readable by Humans | No | Yes (XML) |
| Mesh Errors | Frequent (non-manifold geometry, holes and self-intersections) | Prevented by design |
| Compatibility | Universal | Very broad in modern slicers; partial in older CAD software |
| Licensing and metadata | Not supported | Supported (author, description and usage rights) |
| Recommended Usage | Sharing simple geometry and ensuring maximum compatibility | Complete projects, iteration and production |
What Is the STL Format and How Does It Work?
Developed in 1987 by 3D Systems, the STL (an acronym for stereolithography or Standard Triangle Language) remains the most widely used format on the market. It is available on virtually all 3D model platforms, such as MyMiniFactory, Printables, and Cults.
The way it works is simple: it reconstructs the model’s surface using thousands of triangles. A flat, four-sided face is divided into two triangles; a cube, into twelve.
The number of triangles determines the precision. Modeling a human face requires a dense mesh, and that’s where the file size starts to increase. The downside is that this file size adds no additional value: the STL file does not store information about material, color, texture, or the manufacturing process.
The Limitations of STL
The main practical problem with STL files is the frequency of corrupted files. This usually occurs during conversion, forcing the user to repair them with tools such as Netfabb or Meshmixer.
Each repair is an additional step in the workflow. In a production environment handling dozens of parts a day, that step multiplies.
On top of that, STL files are unreadable to humans: only compatible software can interpret them. If something goes wrong, there’s no way to open the file and figure out what’s happening.
The more accurate the STL file is, the more triangles it will contain.
What Is the 3MF Format, and What Advantages Does It Offer?
The 3MF (3D Manufacturing Format) was created in 2015 by a consortium led by Microsoft, with Dassault Systèmes, Autodesk, Stratasys, and Ultimaker among its founding members. 3D Systems, the creator of STL, joined the consortium at its launch.
Unlike the STL, a 3MF file is not just a mesh. It is a compressed container (similar to a .zip file) that includes the model and all the information needed to manufacture it: manufacturing methods, materials, assemblies, and parameters.
Furthermore, the 3MF format is encoded in XML. If you change the .3mf extension to .zip, you can open the file and examine each of its components. This transparency makes it possible to understand meshing errors.
By design, the format avoids geometric manifold issues: self-intersections, non-manifold models, and holes in the mesh.
The Current Limitations of 3MF
The main barrier to 3MF is not its technical properties, but its adoption. STL remains much more widely available on download platforms.
Two other issues also persist: some older CAD programs do not support it, and interoperability between slicers is not complete. A parameter configured in one slicer is not always transferred correctly to another when opening the same project.
Since 3MF is an open, XML-based format, these issues can be gradually corrected with each new version. The shortcomings of STL, on the other hand, stem from its very design: there is no way to add information that was never intended to be included.
STL vs 3MF: Which One to Choose Based on Your Project
There is no clear-cut winner. The choice depends on your goal:
- Choose STL if you need maximum compatibility, are sharing simple geometry without associated parameters, or are working with older software that doesn’t support 3MF.
- Choose 3MF if you’re working with multiple materials or colors, iterating on the same part, collaborating with third parties, or want to preserve licenses and metadata within the file.
- Choose both if you’re publishing models for a broad community: uploading the 3MF as the main file and the STL as an alternative covers all users.
By 2026, the trend is clear. The leading slicers on the market (PrusaSlicer, OrcaSlicer, Bambu Studio, Cura) natively support 3MF projects, and several already use it as their default save format.
Why STL Is Still Around Despite the Advantages of 3MF
STL isn’t going away anytime soon. Nearly four decades of use have given it a momentum that’s hard to break, and its universal compatibility remains a compelling argument.
But the direction of the industry is clear. The leading slicers already save projects natively in 3MF, and 3D Systems, the company that created STL in 1987, joined the 3MF Consortium at its launch.
For any workflow involving collaboration, iteration, or mass production, 3MF is now the most practical option. For sharing simple geometry and ensuring it opens anywhere, STL still gets the job done.
Frequently Asked Questions about STL vs. 3MF
What is the difference between an STL file and a 3MF file?
The main difference is the amount of information they store. An STL file stores only the part’s geometry using a triangle mesh. A 3MF file stores that same geometry plus color, textures, materials, orientation, supports, and print parameters—all within a single XML-encoded compressed file.
Which format is better for 3D printing, STL or 3MF?
3MF is technically superior for most professional workflows: it’s smaller in file size, prevents mesh errors, and preserves print parameters. STL is still preferable when universal compatibility is needed or when working with older CAD software that doesn’t support the 3MF format.
Why is the STL format still the most widely used?
Because it’s ubiquitous and highly compatible. STL has been around since 1987 and works with absolutely every slicer and CAD program on the market. Major model platforms like MyMiniFactory and Cults host millions of files in this format, which keeps it relevant despite its technical limitations.
Can you open a 3MF file to view its contents?
Yes. A 3MF file is a compressed container similar to a .zip file. By changing the .3mf extension to .zip and unzipping it, you can access the internal XML files and view the geometry, materials, and stored parameters. STL files do not allow this direct viewing.
Can I convert an STL file to 3MF?
Yes. Most modern slicers, such as PrusaSlicer, OrcaSlicer, Bambu Studio, or Cura, allow you to import an STL file and export it as a 3MF project. Keep in mind that the conversion does not recover information that the STL never contained: color, material, and parameters must be configured manually before exporting.
Why is a 3MF file smaller than an STL file?
Because 3MF uses compression and a more efficient data structure. STL describes each triangle independently and repeats coordinates for shared vertices, which inflates the file size in high-resolution models. 3MF references those vertices only once and compresses the entire model.
Do you prefer 3MF files or STL files? Let us know in a comment below or on our LinkedIn or Facebook pages! Plus, don’t forget to sign up for our free weekly Newsletter to get the latest 3D printing news straight to your inbox. You can also find all our videos on our YouTube channel.
*Cover photo credit: Featuring @Josip1996 via Maker World
“Another problem with STLs is the frequency of damaged files. When a file is defective, which is regularly due to a problem during conversion, the user is forced to repair it.”
This would be an incorrect conclusion. The larger reason that (.STL) files are bad is because of bad modeling habits. (i.e. open edges, flipped normals….etc). There’s no file format that can get around bad modeling and that’s something that the 3MF teams needs to come to terms with. Education about the why of something is just as important to this process as any other.
3MF, as just about any other file format, also does not make a universal file for, and it doesn’t have to be every process, but more than one. For example, saving a file for FDM and what materials can be wouldn’t be helpful for Polyjet, SLS, or SLA printing because the geometric considerations needed for those different processes has to be designed as part of the process.
Unitless….. this one I go back and forth on. Yes it’s not included in the file but generally switching from “in” to “mm” or vice versa resolved this issue. For a file format that has existed for so long and that tens of thousand of people and companies were printing prototypes out with for decades seems like a misnomer. Are the pluses for 3MF, sure, but if this is going to be THE file format of the future there’s SO much more that needs to be address outside of what’s listed in the article.