Printhaus accepts both formats
Whether you upload an STL or a 3MF, Printhaus will price and produce your print. You don't need to convert between formats before uploading — just use whichever file you have.
What is an STL file?
STL stands for Standard Triangle Language (sometimes called Stereolithography, after the process it was designed for). It was created in 1987 by 3D Systems — the same company that built the first commercial 3D printer — and has remained largely unchanged ever since.
An STL file describes the surface of a 3D object using a mesh of triangles. The more triangles, the more detailed the surface. That's essentially all it does — there's no colour information, no units, no material data, and no print settings stored in the file itself.
STL strengths
✓ Works with every slicer ever made
✓ Accepted by every 3D printing service
✓ Default format on Thingiverse, Printables, Cults3D
✓ Simple — just geometry, nothing else
✓ Decades of battle-tested reliability
STL weaknesses
✗ No colour, texture, or material data
✗ No units — mm and inches look identical
✗ No print settings stored in file
✗ Large file sizes for complex geometry
✗ Prone to mesh errors (holes, non-manifold edges)
What is a 3MF file?
3MF stands for 3D Manufacturing Format. It was created in 2015 by the 3MF Consortium — a group that includes Microsoft, Autodesk, HP, Stratasys, Dassault Systèmes, and others — specifically to address everything STL can't do. In June 2025 it became an international standard: ISO/IEC 25422:2025.
A 3MF file is structured like a ZIP archive containing XML data. That means it can store far more than just geometry — colour, materials, units, part orientation, print settings, and even assembly information can all live inside a single 3MF file. It also stores vertex data more efficiently than STL, which typically makes 3MF files significantly smaller than their STL equivalents.
One significant advantage: the 3MF specification requires files to be manifold — meaning it's structurally impossible to create a valid 3MF with the mesh errors (holes, flipped normals, non-manifold edges) that frequently plague STL files. Fewer errors means fewer failed prints.
3MF strengths
✓ Stores colour, texture, and materials
✓ Stores units — no ambiguity
✓ Embeds print settings and orientation
✓ Smaller files than equivalent STL
✓ Manifold by spec — far fewer errors
✓ ISO international standard (2025)
✓ Supports multi-material and multi-colour
3MF weaknesses
✗ Not supported by very old software
✗ Less common on design sharing sites (changing fast)
✗ Converting from STL doesn't add back lost data
✗ Some slicer settings don't transfer between different printers
STL vs 3MF: side-by-side comparison
| Feature | STL | 3MF |
|---|---|---|
| Created | 1987 (3D Systems) | 2015 (3MF Consortium) |
| Standard status | Industry convention | ISO/IEC 25422:2025 |
| Stores geometry | Yes | Yes |
| Stores colour | No | Yes |
| Stores units | No | Yes |
| Stores print settings | No | Yes |
| File size | Larger (uncompressed) | Smaller (ZIP compressed) |
| Error resistance | Prone to mesh errors | Manifold by spec |
| Multi-material | No | Yes |
| Human readable | No (binary) | Yes (XML inside) |
| Compatibility | Universal | All modern tools |
| Files on Printables | Majority | Growing fast |
| Printhaus support | Yes | Yes |
When to use STL, and when to use 3MF
Use STL when:
You downloaded the file from Printables, Thingiverse, or Cults3D
The vast majority of files on these platforms are STL. Just upload it directly — no conversion needed.
You're sharing a design with an unknown audience
STL is universally understood. If you're not sure what software the recipient uses, STL is the safe default.
Your CAD tool only exports STL
Some older or simpler tools (early TinkerCAD exports, some online converters) only produce STL. That's fine — upload it and Printhaus will handle the rest.
It's a simple single-colour, single-material print
For a plain PLA keyring or phone stand, STL contains everything Printhaus needs.
Use 3MF when:
Your design has multiple colours or materials
3MF is the only format that carries colour and multi-material assignments through the full workflow. STL would lose this information entirely.
You're designing from scratch in modern CAD software
If you're working in Fusion 360, SolidWorks 2019+, Blender, or FreeCAD, export 3MF from the start. You get a smaller file with more information.
You want to preserve orientation and assembly information
3MF stores part orientation and relative positions. Useful if your design has a specific intended print orientation that matters for quality.
You're building a professional workflow
3MF is now ISO/IEC 25422:2025 — an international standard. For serious commercial production, it's the format the industry is moving toward.
Which software supports 3MF?
3MF support has grown dramatically — over 100 applications support it as of 2025. Here's a quick reference:
Slicers with 3MF support
• PrusaSlicer — native format
• Bambu Studio — default export
• Cura 5.0+ — full read/write
• Simplify3D 5.0+
• Microsoft 3D Builder
CAD tools with 3MF export
• Fusion 360
• SolidWorks 2019+
• FreeCAD
• Blender
• TinkerCAD
• Onshape
How to convert STL to 3MF (and back)
The easiest route is through your slicer. Open PrusaSlicer, Bambu Studio, or Cura, import your STL, then use File → Export → Export as 3MF (the exact label varies by app). The resulting 3MF will have the same geometry plus the 3MF container structure — but it won't magically gain colour or unit data that was never in the original STL.
Going the other way (3MF to STL) follows the same process: open the 3MF in any of the above tools and export as STL. Note that any colour, material, or settings data in the 3MF will be lost in the conversion — STL simply cannot store it.
For Printhaus users — no conversion needed
Printhaus accepts both formats directly. Upload whichever file you have and the system will handle the rest. If you're uploading a multi-colour design, 3MF preserves that information — but for standard single-colour PLA prints, STL works perfectly.
The verdict
3MF is the better format — technically superior in almost every measurable way, and now an international ISO standard. If you're building a new workflow from scratch, use 3MF throughout.
But STL isn't going anywhere. The existing library of STL files on design sharing sites is enormous, and "works with everything" is a genuinely useful property. For most people downloading a design and sending it to Printhaus, STL is fine and requires no conversion.
The practical rule: use whatever format your design tool or download source gives you. If you have a choice and your model has colour or materials, use 3MF. If your model is a simple single-colour print and you already have an STL, just upload it.
Frequently asked questions
What is the difference between STL and 3MF files?+
STL (1987) stores only surface geometry — no colour, no units, no print settings. 3MF (2015, ISO standard 2025) stores geometry plus colour, materials, units, orientation, and print settings in a single compressed file. 3MF files are typically smaller and less prone to mesh errors.
Should I upload STL or 3MF to Printhaus?+
Printhaus accepts both. For most single-colour prints, either works fine. If your design has multiple colours or complex assemblies, upload 3MF. If you downloaded from Printables or Cults3D, you'll likely have an STL — that's fine to upload directly.
Is 3MF better than STL?+
3MF is technically superior in almost every way — smaller files, more data, fewer errors, and now an ISO standard. However, STL remains the most universally compatible format. For Printhaus uploads, either works.
Can I convert STL to 3MF?+
Yes. PrusaSlicer, Bambu Studio, and Cura 5.0+ can all open an STL and re-export as 3MF. Note that conversion adds the 3MF structure but cannot recover information (like colour) that was never in the original STL.
What software exports 3MF files?+
Fusion 360, SolidWorks 2019+, FreeCAD, Blender, TinkerCAD, and Onshape all export 3MF. PrusaSlicer uses it as its native format, Bambu Studio uses it as default. Cura 5.0+ has full read/write support.
Why are most files on Printables and Thingiverse still STL?+
STL has been the default since 1987 — the vast majority of models were uploaded before 3MF gained traction. Both platforms now accept 3MF, and newer designs increasingly offer it, but the existing STL library is enormous and will remain dominant for years.