3MF to GCode: Slice a 3MF File Online
Drop a .3mf file and slice it to a .gcode file for a single-material printer. The tool reads the unit stored in the 3MF, applies the placement of every object on the build plate, merges them into one model on your bed and shows the layers before you download. It runs in your browser and does not generate supports.
How to slice a 3MF file to GCode
- 1
Open the 3MF
Drop the .3mf file. It is a ZIP package, so the tool unpacks it on your device and reads the mesh of every object on the build plate.
- 2
Check the merged model
The objects are combined into one model and set down on the bed. Check the size in millimetres; the unit written in the file has already been applied.
- 3
Pick printer and filament
Choose a printer preset or a custom bed, then the material, layer height, walls and infill. Open the advanced section for speeds, retraction and start G-code.
- 4
Slice, preview, download
Press Slice, drag the layer slider to check each layer, then download the .gcode and check its start G-code and temperatures for your printer.
What happens to a 3MF file here
3MF carries more than a plain mesh. This is how each part of it is treated so you know what ends up in the G-code.
| Units | Read from the file (millimetre, centimetre, inch, metre and so on) and converted to millimetres. |
|---|---|
| Several objects | All objects on the build plate are merged into one model; none are removed or sliced one by one. |
| Placement | Item and component transforms in the file are applied, then the model is centred on your bed. |
| Colours and materials | Ignored. The output is a single-material print with one nozzle. |
| Slicer project settings | Ignored. Settings from the file's creator are not read; you set them here. |
| File and mesh limits | Up to 100 MB and 1.5 million triangles in total. |
| Supports | None are generated, and any support geometry stored in the file is printed as ordinary model. |
Why a 3MF is not just an STL
A 3MF file is a ZIP package. Inside are one or more XML model parts that hold the triangle meshes, a list of build items with their positions, and often thumbnails, colours and settings. Unlike an STL, it says what unit its numbers are in, so a part drawn in inches arrives at the right size. That is the main reason people ask for a 3MF to GCode route: the model arrives scaled and placed the way its author meant.
This slicer reads the unit, resolves the components and the transform of each build item, and flattens everything into one set of triangles in millimetres. If the file holds a whole plate of parts, they are sliced together as one print job, in the positions they were given, so keep the objects apart on the plate or they will merge into a single lump.
What is left out, and why
Settings stored by the program that wrote the 3MF, such as layer height, infill or per-object overrides, are not read. They differ between programs and cannot be mapped reliably to another slicer, so set them in the form instead. The same goes for colours, multiple materials and modifier volumes: the slicer makes one material from one nozzle.
There are no supports and no tree supports. If a 3MF was prepared with support structures as separate geometry, they print as ordinary solid parts because the slicer cannot tell them apart. Planar layers only: no variable layer height, no ironing and no gap fill. For parts that need those features, use a full desktop slicer. Keeping the feature list short is deliberate: every line the page does not guess is a line you can see and change yourself in the form, and the warnings after slicing tell you when something in the file was skipped.
Before you print the G-code
Look at the layer preview from the first layer to the last. Make sure each object is where you expect, and that nothing floats above the bed with no support. Open the advanced section and read the start G-code, since a printer that needs its own homing or levelling macro will not get it unless you add it. Check the nozzle and bed temperatures for your filament.
Print a small part first, and watch the first layer. If the model looks the wrong size, check the unit and the scale value in the size box. A part that comes out 25.4 times too large or small was almost always saved with the wrong unit. When a file holds several parts, slice once to see them together, then read the warnings under the result: they list thin features that were dropped, open edges in the mesh and any skirt that had to be left out because the part fills the bed.
No model to print yet?
Make a printable 3D model from a photo or a short text prompt with AI, or turn a picture straight into an STL, then bring it back here and slice it for your printer.
More free slicing and 3MF tools
3MF to GCode questions
Check the start G-code and temperatures for your printer before printing, and watch the first layer. This slicer only writes a file: it never sends anything to a printer. Print time is an estimate. Marlin and Klipper are named only to describe the G-code dialects; 3D AI is not affiliated with their projects.