STL vs 3MF - A Comparison of 3D Printing File Formats

guidesoftware

Jul. 23

When preparing a 3D model for printing, the file format you use is important. The two most common formats are STL and 3MF. But what exactly are these formats, and how do they compare for 3D printing applications?

About STL Files

STL, short for stereolithography, has been the standard format for 3D printing for decades. An STL file describes the surface geometry of a 3D model using triangular polygons (triangles). It contains no additional information - just the mesh data.

Pros:

Supported by all 3D printers and slicers
Simple and lightweight

Cons:

No scale, color, or material data
No validation - can contain holes, bad edges, etc.
Only one object per file

About 3MF Files

3MF or 3D Manufacturing Format is an XML-based format developed by Microsoft and the 3MF Consortium as an improved open standard for 3D printing.

A 3MF file can contain:

Multiple objects
Full slicer settings
Materials, colors, and textures
Metadata like units and identifiers
Built-in validation to prevent errors

3MF uses ZIP compression for smaller files. Instancing can reduce size by reusing identical mesh data.

STL vs 3MF Comparison

Here’s how the two formats compare:

  
    STL
    3MF
  
    Capabilities
    Contains only geometry
    Can store full models, configurations, materials, etc.
  
    Validation
    No safeguards against flaws
    Validates to prevent errors
  
    Support
    Wider compatibility
    Support is growing
  
    Ease of Use
    Simpler
    Allows greater complexity
  
    Multiple Items
    Limited to one object
    Can combine multiple
  
    Editability
    Geometry edits require re-slicing
    Models can be repositioned without re-slicing
  
    Sharing
    Shares raw geometry
    Can share full configured models

When To Use Each Format

For most desktop FDM/FFF 3D printing applications, STL is still the best choice due to wider compatibility and simplicity.

However, for more advanced 3D printing, 3MF allows greater flexibility:

Full color 3D printing - Store color data for each triangle
Multi-material printing - Define different materials in one file
Model assemblies - Print interconnected parts together
Embedded metadata - Include printing/assembly instructions

While 3MF has clear advantages, it does require more advanced knowledge to leverage its capabilities fully. As software support continues to grow, 3MF will likely become more popular, especially for complex printing applications. But good old STL is still perfectly suitable for sharing raw geometry, and will remain the "least common denominator" format for years to come due to its simplicity and universality.

In summary, 3MF unlocks exciting new potential, but STL retains the advantage of broad compatibility and ease of use. Consider your specific printing needs when choosing the right format. Both have an important place in 3D printing's ecosystem.