STL · 3MF

STL vs 3MF

Both formats carry a mesh to a slicer. 3MF adds what STL lacks: a declared unit, colours, materials and a build plate that can hold several objects.

Criterion	STL	3MF
What it stores	Triangles only	Mesh, units, materials and objects
Units	None; millimetres are assumed	Declared in the file, usually millimetres
Colours and materials	None	Base colours and materials
Several objects	Shells without names	Objects with names and placement
Slicer support	Universal	Modern Bambu Studio, PrusaSlicer and Cura
File size	Small	Larger ZIP/XML package

In short. Use 3MF when your slicer supports it and you care about units, colours or multi-object plates. Keep STL as the universal fallback for older tools and simple meshes.

Convert between them

Convert 3MF to STL Convert STL to 3MF

Format pages

STL: the triangle-only format 3MF: units and materials in one package

Questions

Is 3MF better than STL?+

For modern slicers yes: units, colours and objects. STL stays the safest fallback.

Can I convert 3MF to STL?+

Yes, but colours, materials and object names are lost.

Why is my 3MF the wrong size?+

Check the import unit in your slicer; 3MF declares one, STL does not.