3MF against STL
STL stores triangles. 3MF stores the same triangles plus everything around them.
What does STL leave out?
| What | 3MF | STL |
|---|---|---|
| Units | yes | no |
| Several named objects | yes | no |
| Placement on the plate | yes | no |
| Colours and materials | yes | no |
| Print settings | yes | no |
Which one is smaller?
Usually the 3MF, because it is compressed. The preslice sample file is 58 KB as 3MF and 90 KB as STL.
When is STL fine?
For a single part with one colour. Every tool reads STL. Open an STL in
preslice and click Convert to 3MF to get a .3mf.
What about OBJ?
| What | OBJ | 3MF |
|---|---|---|
| Units | no | yes |
| Several named objects | yes | yes |
| Colours | in a separate .mtl file |
yes |
| Print settings | no | yes |
OBJ is the right pick when another tool needs it, such as Blender. See OBJ to 3MF.
Is 3MF an actual standard?
Yes: the 3MF Core Specification, published by the 3MF Consortium and standardised as ISO/IEC 25422:2025. STL has no standard.