3MF viewer
Open a .3mf and see it in colour, parts and all — the detail STL throws away. A quick look at a MakerWorld or Printables download before it goes to the slicer, with nothing installed and nothing uploaded.
The .3mf is parsed locally and never uploaded. It shows the model geometry, colour and separate parts — not a slicer's print settings, which stay with the app that made them.
3MF is what STL should have been
STL has been the 3D-printing standard for forty years, and it shows: it's bare triangles with no colour, no units and no way to hold more than one object cleanly. 3MF is the modern answer — a ZIP container of XML that keeps the meshes, their colour and materials, multiple build items and print metadata all in one self-describing file. It's backed by a consortium that includes Microsoft, Autodesk, HP and Prusa, and every current slicer reads it.
That's why multi-colour and multi-material printing has moved to 3MF — a Bambu AMS print or a multi-plate layout simply can't survive as an STL. Where STL forces you to guess units and ship one shell at a time, a 3MF arrives knowing its own scale and carrying every part together.
What I check on a 3MF
- 1. How many parts
- 3MF can hold a whole plate of objects in one file. If the mesh count below is more than one, expect several build items — handy for multi-part prints, worth knowing before you slice.
- 2. Colour and material
- Unlike STL, 3MF can carry colour and per-object materials, so a multi-colour model shows up in colour here. Grey means the file didn't store any — the geometry is all there is.
- 3. Real dimensions
- 3MF records explicit units (millimetres), so the size below is trustworthy — none of the unit guesswork STL forces on you.
- 4. Triangle count
- Same slicer reality as any mesh: a few hundred thousand triangles is comfortable, millions on a simple part means it was over-tessellated.
3MF vs STL, at a glance
| 3MF | STL | |
|---|---|---|
| Colour / material | Yes | No |
| Units | Explicit (mm) | None (mm assumed) |
| Multiple parts | Yes | One shell |
| Universally accepted | Modern slicers | Everything |
Use 3MF when your slicer takes it and you want colour, parts and honest units. Keep STL in your back pocket for the one tool or service that only speaks triangles.
How to view a 3MF file
- 1Click “Open 3MF file,” or drag your .3mf onto the viewer — it loads locally, with no upload.
- 2Drag to orbit; a multi-colour or multi-part 3MF shows its colour and separate objects.
- 3Read the part count, real millimetre dimensions and triangle count below before you slice.
3MF viewer — FAQ
- 3MF or STL — which should I use for printing?
- If your slicer supports 3MF (Bambu Studio, PrusaSlicer, OrcaSlicer and Cura all do), 3MF is the better file: it keeps units, colour and multiple parts in one place, where STL drops all of that. Reach for STL only when you need maximum compatibility with an older tool or service that won't take anything else.
- Why doesn't my Bambu or Prusa project fully open here?
- A .3mf saved by a slicer is usually a whole project — plate layout, print settings, supports, sometimes G-code — wrapped around the geometry. This viewer shows the model and its parts, not the slicer's settings. To reopen the full project, use the slicer that made it.
- Does 3MF really keep colour?
- Yes. 3MF stores colour and material per object, which is the main reason it's replacing STL for multi-colour and multi-material printing (think AMS on Bambu machines). A multi-colour 3MF renders in colour here; STL never could.
- What is a .3mf file, exactly?
- It's a modern 3D-printing format: a ZIP container holding XML that describes the meshes, their colours and materials, multiple build items and print metadata. Think of it as the tidy, self-describing successor to STL, backed by a consortium including Microsoft, Autodesk, HP and Prusa.
- How do I open a 3MF without a slicer?
- Right here — drop the file and it renders in the browser, nothing installed. That's useful for a quick look at a MakerWorld or Printables download before you commit it to a slicer and a print.
- Can I convert a 3MF to STL?
- Yes — if a tool in your chain only accepts STL, flatten the 3MF down to geometry with the 3MF-to-STL converter below. You'll lose the colour and part separation, which is exactly the trade STL forces.
Do more with your 3MF
Flatten it to STL for an older tool, or open a different format.
Need a model to print?
Describe it or drop in a photo — Sculptor generates a print-ready 3D model you can export and open right back here.
Generate a 3D model