Tools · 3D Converter

Convert 3MF to STL online

3MF stores a print job: objects, their positions on the plate, a unit and often colours and slicer settings. STL keeps only the triangles. The converter reads the unit of the 3MF (millimetre, centimetre, inch and others), applies the transform of every build item and writes one binary STL in millimetres with a watertight check.

Your files never leave your device

Drop a file to see it here.

Convert to

FBX is not offered as output: browsers cannot write clean FBX files. Every Grab3D library model comes with a ready FBX download. Browse models

3D printing preset: millimetres, Z-up, origin at the bottom center

STL stores geometry only. All visible parts are merged into one binary STL.

Up axis Unit

Origin Recompute normals (smooth, sharp edges above 30°) Simplify materials (base color and color texture only) Bake colors and textures into vertex colors

Read the source as

Up axis of the source Unit of the source

Auto uses the file information: STL is millimetres Z-up, 3MF uses the unit stored in the file with Z-up, FBX uses its unit scale, everything else metres Y-up.

How it works

Drop the .3mf file. Project files from slicers with several objects work too.
Look at the dimensions in the info panel. They already include the unit stored in the 3MF, so an inch file arrives at its real size.
Keep the 3D printing preset on, convert, read the edge check and download the STL.

What is kept and what to watch

Lost in STL: colours, materials, textures, print settings, supports and the plate layout. Keep the 3MF for your slicer and use the STL where only geometry counts.
All objects of the build are merged into one STL at their positions from the 3MF. They stay separate shells, they are not fused.
Tested with files in millimetres, centimetres and inches, with several build items, rotations and components, also split across model parts. Rare extensions such as beam lattices or slices are not read.

Other conversions

Frequently asked questions

Does the STL keep the size of my 3MF?

Yes. A 3MF records its unit, and the converter applies it before writing millimetres. A 2 inch cube becomes 50.8 mm, a 2 cm cube 20 mm. Both cases were measured again with an independent STL reader.

Why does the STL have several separate parts?

Every build item of the 3MF stays its own shell at its place on the plate. Slicers print that as it is, and you can arrange the parts again after the import.

Can I get one STL per object?

Not yet. The converter writes all objects into one file. To split them, use the separate parts feature of your slicer or a 3D program.