OBJ to 3MF Converter
Take a Blender export into a slicer in the format slicers actually prefer.
Drop a file here. It never leaves your browser.
No sign-up · no upload · no watermark · no file size limit · 3MF first, STL and STEP one click away
Have a different file? STL to 3MF Converter · PLY to 3MF Converter · STEP to 3MF Converter
How to convert an OBJ to 3MF
Add your OBJ
Drop an OBJ onto the tool, or click to choose one. It is read in your browser and never uploaded.
Check the preview
Drag the model to turn it. The triangle count, the number of parts and the size in millimetres are shown under it, so a unit problem is visible before you download.
Download 3MF
Click Download 3MF. No account, no watermark, no waiting. STL and STEP come off the same file with one more click.
What happens to your file
The OBJ is read as a vertex list and a face list. Faces with four or more corners are fanned into triangles, which is correct here because OBJ polygons are planar and convex by definition, and negative indices are resolved against the vertices seen so far, which is how a file written as a stream of separate objects refers to its own geometry. Materials, texture coordinates and normals are read past: 3MF has no way to carry them, and pretending otherwise would only make the file bigger.
Starting from a photo or a drawing instead of a mesh? That is the image to STL converter, and a 2D outline becomes a solid on the DXF to STL converter.
About formats
OBJ was created by Wavefront Technologies in the 1980s for its Advanced Visualizer animation software and became a universal interchange format because it is plain text anyone can read. A file is a list of vertices, then faces referring to those vertices by 1-based index, with optional texture coordinates and normals; a companion .mtl file carries materials, and colour lives there rather than in the geometry. Unlike STL, OBJ faces may have any number of corners and vertices are shared rather than repeated three times per triangle, so the same shape is usually a smaller file and the mesh keeps its topology, which matters if it will be edited again. What OBJ has never had is a unit: the numbers are bare, so a model is only at the right size if everyone agrees on what one unit means, and that ambiguity is the usual reason an OBJ lands in a slicer a thousand times too big or too small. Every DCC tool reads and writes it, which is why it remains the practical bridge between modelling software and everything else.
- Developer:
- Wavefront Technologies
- Initial release:
- 1980s
Frequently asked questions
How do I convert an OBJ file to 3MF?
Drop the OBJ onto the tool on this page and click Download 3MF. It is read and converted by JavaScript running in your browser, so there is nothing to install, no account to make and no queue to wait in. STL and STEP come off the same file with one more click.
Is this OBJ to 3MF converter free?
Yes. Free, no watermark, no file size limit, and no account needed to convert or to download. There is no paid tier of this tool to upsell you to.
Is my file uploaded anywhere?
No. The file is opened by code running in your browser tab and never sent to a server, which also means nothing is stored, logged or scanned. You can disconnect from the internet once the page has loaded and the converter keeps working. For a client's part under NDA that is the difference between usable and not.
What happens to the materials and textures?
They are dropped, because STL and 3MF geometry cannot carry them. An OBJ keeps colour in a companion .mtl file and texture coordinates alongside the faces; neither has a destination here. If the model is going to a single-material printer this costs you nothing.
My OBJ has quads. Is that a problem?
No. Quads and larger polygons are fanned into triangles, which is exact rather than approximate: OBJ polygons are planar and convex by definition, so the triangles describe the same surface. The triangle count in the result will be higher than the face count in the OBJ, which is expected.
Is there a file size limit?
None imposed by the tool. The practical limit is your own machine's memory, since the file is held in the browser tab; a few hundred megabytes is fine on a desktop and less so on a phone. Nothing is queued or throttled because there is no server involved to queue it.