How to convert STL to 3MF
- Drop one or several
.stlfiles above (binary and ASCII STL both work; OBJ too). - Untick anything you don't want, then keep 3MF selected.
- Click Download 3MF. Every STL becomes a named object in one 3MF file.
Why switch from STL to 3MF
- Smaller files. 3MF is a compressed archive and stores each corner once, so it is usually several times smaller than the same model in STL.
- Units are explicit. STL has no units; 3MF says millimetres, so the model can't load 25.4 times too small.
- Many objects in one file. Send one 3MF instead of a folder of STLs, with object names preserved.
- Colours. OBJ files with an MTL keep their colours in the 3MF.
Read more in 3MF vs STL.
Frequently asked questions
Does STL to 3MF conversion change my model?
No. Coordinates are kept exactly; identical corners are merged so the mesh is indexed. If you leave Center on the bed on, the whole set is moved so it sits centred at height zero.
Can I convert several STL files at once?
Yes. Drop them together; they end up as separate objects in one 3MF. Tick One file per object if you want one 3MF per STL instead.
Will Bambu Studio or PrusaSlicer open the result?
Yes. The output follows the core 3MF specification, which every major slicer reads.
My STL is in inches. What do I do?
STL files don't record units. Import the 3MF into your slicer and scale by 2540% (inches to millimetres) if it looks tiny.