Understanding 3D File Formats: STL vs OBJ vs 3MF

You've designed your model or downloaded it from the internet, and now you need to get it printed. But wait—should you export as STL, OBJ, or 3MF? Does it even matter?

The short answer: yes, it matters. The file format you choose affects print quality, color options, and how much tweaking your print service needs to do. Here's what you need to know.

STL: The Old Reliable

STL (Standard Tessellation Language) has been around since 1987—older than most people reading this post. It's the default format for 3D printing and the one you'll encounter most often on sites like Thingiverse, Printables, and MakerWorld.

What STL does well:

• Works with virtually every 3D printer and slicer
• Simple format that's fast to process
• Small file sizes for basic geometry
• Every 3D printing service accepts it

What STL lacks:

• No color or texture information
• No material data
• No scale information (we have to trust your settings)
• Uses only triangles to define surfaces, which can make curves look faceted
• Prone to errors like holes, inverted faces, and non-manifold geometry

The STL Problem Nobody Talks About

Here's the thing about STL files: they break. A lot. When you export from CAD software, the conversion process can create holes in the mesh, flip faces inside-out, or generate overlapping geometry that confuses slicers.

When we receive an STL file with issues, we have to repair it before printing. Tools like Microsoft 3D Builder, Meshmixer, or the repair functions built into Bambu Studio can fix most problems automatically. But sometimes the repairs change your model slightly—especially around fine details.

This isn't a dealbreaker for most projects. Just know that if you're sending STL files, there's always a small chance something needs fixing on our end.

OBJ: Color Gets Involved

OBJ (Object File Format) came from the graphics and animation world before 3D printing was even a thing. It gained popularity in printing when multi-color became more accessible.

What OBJ brings to the table:

• Supports color and texture information
• Uses multiple polygon types (not just triangles), allowing smoother curves
• More precise surface representation than STL
• Good compatibility across modeling software

The OBJ catches:

• Color data lives in a separate MTL (Material Template) file
• If you send an OBJ without its MTL, you get no color
• No scale information—if your software doesn't agree on units, your 10cm model might show up at 10 inches
• Larger file sizes than STL

When OBJ Makes Sense

OBJ is your go-to when you need to print something with multiple colors or textures baked into the model. Think painted figurines, architectural models with different material zones, or anything where color is part of the design, not just a surface finish.

The downside is that OBJ's two-file system (OBJ + MTL) creates room for error. We've seen plenty of color prints arrive as solid gray because the MTL file got lost somewhere along the way. If you're sending an OBJ, zip both files together.

3MF: The Modern Standard

3MF (3D Manufacturing Format) was developed in 2015 by a consortium that includes Microsoft, Autodesk, HP, and Stratasys. It was designed specifically for 3D printing, and it shows.

Why 3MF is genuinely better:

• Everything in one file: geometry, colors, textures, materials, and scale
• Compressed format means smaller file sizes despite containing more data
• XML-based structure that's human-readable and easier to debug
• Built-in error checking means files are almost always printable without repairs
• Supports multiple objects and build platforms
• Can include print settings like infill and layer height

The 3MF reality check:

• Not every modeling tool exports 3MF natively (though most modern ones do)
• Some older slicers and services don't support it
• The format is still evolving, so compatibility can vary

3MF and Bambu Lab Printers

If you've used Bambu Studio or downloaded files from MakerWorld, you've probably noticed 3MF files everywhere. There's a reason for that.

Our BambuLab P1S and H2S printers work seamlessly with 3MF. The format can include all print settings—support placement, infill patterns, even plate arrangements for multi-part prints. When you download a 3MF from MakerWorld, it often comes pre-configured for optimal printing on Bambu hardware.

This means less guesswork for you and more consistent results. When someone sends us a 3MF with settings included, we know exactly how the creator intended it to be printed.

Quick Comparison

| Feature | STL | OBJ | 3MF | |---------|-----|-----|-----| | Color support | No | Yes (separate file) | Yes (embedded) | | Scale info | No | No | Yes | | Material data | No | Limited | Yes | | Print settings | No | No | Yes | | File size | Medium | Large | Compact | | Error-free | Rarely | Sometimes | Usually | | Universal support | Excellent | Good | Growing |

Which Format Should You Use?

Use STL when:

• Your model is single-color
• You downloaded it and that's what's available
• Maximum compatibility matters more than features
• The file is simple geometry without fine surface details

Use OBJ when:

• You need multi-color or textured printing
• Your modeling software exports it better than 3MF
• You're working with animation or rendering software that prefers OBJ

Use 3MF when:

• You want the most reliable printing experience
• Your model includes colors, materials, or multiple parts
• You're designing for Bambu Lab printers
• You want to include recommended print settings
• You want to avoid mesh repair issues

A Note on File Prep

No matter which format you choose, a few things make our lives easier:

Check your scale. A model designed at 100mm that imports at 100 inches is a headache for everyone. If you're not sure, add a note with your intended dimensions.

Export at appropriate resolution. STL files let you control the number of triangles. More triangles mean smoother curves but larger files. For most prints, a 0.01mm tolerance or "high" preset works well.

Keep your mesh watertight. Before exporting, run a mesh analysis in your CAD software. Most programs can identify holes, non-manifold edges, and inverted normals before they become problems.

When in doubt, send 3MF. It's 2025—most modern software supports it, and the benefits are real.

The Bottom Line

STL will keep working for years to come—it's too established to disappear. But 3MF is the future, and it's already the present for anyone using Bambu Lab or other modern printers. If your software supports it, 3MF should be your default choice.

OBJ has its place for color work, but the split-file system makes it clunky compared to 3MF's all-in-one approach.

The best format is the one that works for your specific project. Simple prototype? STL is fine. Multi-color display piece? OBJ or 3MF. Complex assembly with print settings? 3MF, no question.

Ready to Print?

Have a model you want to bring to life? Whether it's STL, OBJ, or 3MF, we can work with it. Our BambuLab P1S and H2S printers handle all major formats, and our 250mm³ build volume gives you room for substantial prints.

Upload your file and get an instant quote, or reach out if you have questions about file prep. We're happy to help you get the best results from your design.