3MF vs STL: What Is the Difference and Which Should You Use?

STL describes shape. 3MF describes a complete print job. Here is exactly what each format stores, where 3MF solves real problems that STL cannot, and when STL is still the right choice.

Back to STL Files Guide

The Short Answer

STL stores only the surface geometry of a 3D object as a mesh of triangles. 3MF stores geometry plus color assignments, material properties, print settings, scale and units, multi-part assembly data, and thumbnail previews — all in a single file.

For simple single-color prints where you choose your own settings, STL works fine and will open in anything. For multi-color AMS printing, for sharing files with settings pre-configured, or for complex assemblies where part positions matter, 3MF is the clearly better choice.

Side-by-Side Comparison

Feature	STL	3MF
3D geometry	✓ Yes	✓ Yes
Color per region	✗ No	✓ Yes
Material assignment	✗ No	✓ Yes
Print settings embedded	✗ No	✓ Yes (slicer-specific)
Units and scale	✗ No	✓ Always millimeters
Multi-part assembly	✗ No (separate files)	✓ Yes, with positions
Thumbnail preview	✗ No	✓ Yes
File size	Smaller (binary)	Slightly larger (compressed XML)
Universal compatibility	✓ Everything	Most modern slicers
Created	1987	2015

Woman and man working together on 3D printer design project at a modern workstation

What Is 3MF?

3MF stands for 3D Manufacturing Format. It was developed by the 3MF Consortium, a group formed in 2015 by Microsoft, Autodesk, HP, Stratasys, and other major companies in 3D printing and software. The goal was explicit: create a format that addresses all the limitations of STL that had accumulated over nearly three decades.

A 3MF file is actually a ZIP archive containing XML files, texture maps, and metadata. The human-readable XML structure means any software can implement support for it relatively easily. Unzip a 3MF file and you find a collection of organized text files describing every aspect of the model and its intended print configuration.

The format is open-source and freely licensed. Anyone can implement 3MF support without royalties or restrictions. This is the same approach that made STL’s universal adoption possible — 3MF repeats that strategy with a much richer data model.

3MF in Practice: Bambu Lab

The clearest everyday example of 3MF’s advantage over STL is Bambu Lab’s AMS (Automatic Material System) multi-color printing workflow. When you download a Bambu Studio 3MF project file, it contains the complete model geometry plus the exact color assignments for each region of each part. Open the file and the slicer knows which filament slot to load for each color, how the build plate should be arranged, and what settings apply to each component. Every decision the designer made is encoded in the file.

The equivalent workflow in STL requires separate files per color, manual region painting in the slicer, and separate documentation of settings. 3MF does this in one file automatically.

When to Use Each Format

Use STL when:

Sharing a model that needs to work with any printer, any slicer, any software without compatibility questions
Uploading to a marketplace or repository where broad compatibility matters
Printing a simple single-color functional part where you set your own settings
Working with older software or printers that may not support 3MF
Converting between programs where STL is the common denominator
The model has a single part and single color with no special settings

Use 3MF when:

Printing multi-color models with an AMS or multi-material system
Sharing files where the recipient should use specific settings
Working on Bambu Lab hardware where 3MF is the native format
Assembling multi-part models where part positions matter
Saving and sharing a complete slicer project including settings
You want a thumbnail preview embedded in the file for easy identification

Slicer Support for 3MF

3MF support has become standard in all major modern slicers. The level of support varies by application.

Bambu Studio treats 3MF as its native format. Bambu project files are 3MF files with Bambu-specific slicer settings encoded. Opening a Bambu 3MF file in Bambu Studio recreates the complete project including filament assignments, process settings, and build plate layout.

PrusaSlicer has strong 3MF support for import and export. It reads color and geometry data and can export complete project files in 3MF. Cross-application 3MF compatibility varies — slicer-specific settings in a Bambu 3MF may not translate correctly in PrusaSlicer and vice versa.

Ultimaker Cura supports 3MF import and export. Geometry and basic settings transfer well. Advanced color assignments from other slicers may require manual re-application.

Cross-slicer compatibility note: 3MF geometry and units transfer reliably between slicers. Slicer-specific print settings (temperatures, speeds, process profiles) are stored in proprietary extensions within the 3MF container and do not transfer between different slicer applications. A Bambu Studio 3MF opened in Cura will have the correct geometry but not the Bambu-specific settings.

Frequently Asked Questions

Can I convert an STL file to 3MF?

Yes. Import the STL into any major slicer (Bambu Studio, PrusaSlicer, Cura) and export as 3MF. The geometry transfers correctly and the 3MF will include the units (millimeters) and any settings you configured in the slicer. What you cannot add during conversion is color data or material assignments — those require manual setup in the slicer before export.

Is 3MF better than STL for all purposes?

Not for all purposes. For maximum compatibility across every possible tool and platform, STL remains more reliable. For printing simple single-color models where you set your own settings, STL and 3MF produce identical results. 3MF’s advantages show up specifically in multi-color printing, settings-embedded workflows, and multi-part assemblies. For everyday hobbyist single-color printing, either format works equally well.

Why do most STL marketplaces not offer 3MF?

Two reasons. First, most marketplaces predate widespread 3MF adoption and STL is still what the majority of users expect. Second, 3MF files with embedded slicer settings are often slicer-specific (Bambu Studio settings are not useful to PrusaSlicer users), which reduces the universal value of offering 3MF on a platform serving many different printer types. The trend is toward offering both: STL for universal compatibility plus 3MF for Bambu and other platforms where it adds clear value.

Does 3MF work with older printers?

The printer itself never reads 3MF directly — your slicer reads the 3MF, generates G-code, and sends that G-code to the printer. So 3MF compatibility depends on your slicer, not your printer. If your slicer supports 3MF (all major modern slicers do), your printer receives the same G-code it would have received from an STL workflow. Printers from 2015 work the same as printers from 2024 in this regard.

What does 3MF stand for?

3MF stands for 3D Manufacturing Format. It was named to reflect its purpose as a comprehensive file format for the complete manufacturing workflow, in contrast to STL which only captures the geometry portion of that workflow.