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.objOBJ→.3mf3MFlossless

Convert OBJ to 3MF

Convert OBJ to 3MF in your browser. The conversion runs on this page and the file never leaves your computer.

Drop your .obj file

up to 250 MB · .obj

Free, and it opens in this tab. Nothing is uploaded, and there's no account to make.

Runs locally · nothing uploaded

Before you convert: what this keeps and what it destroys

Preserved

  • The geometry, triangle for triangle
  • Overall dimensions and proportions
  • Watertightness, where the input is watertight
  • The unit, recorded in the file
  • Colour
  • Separate parts and their positions

Destroyed

  • Nothing either format can represent

↺ the reverse: 3MF → OBJ · about .obj · about .3mf · just view it instead

Why people convert OBJ to 3MF

A good move when you have a downloaded mesh and intend to print it. 3MF is smaller, declares its unit, and keeps parts separate, and slicers prefer all three.

OBJ's object names carry over as separate objects on the build plate. Colours don't, unless they were in the .obj itself and not in a .mtl sidecar that never got uploaded.

What you get

You get a binary 3MF file containing the same triangles the OBJ file described. No geometry is added, removed or approximated: mesh-to-mesh conversion is a change of container, and this site's tests check that the triangle count comes out identical.

Carried across: the unit, recorded in the file, colour available in the selected OBJ (external materials are not read), the supported part structure.

The conversion runs in your browser. Your file stays on your computer and is not uploaded.

What to check afterwards

  • OBJ carries no unit. The numbers in the file are just numbers, so the conversion assumes millimetres. Check the overall dimensions of the result before you commit to machining or printing it. A file exported from a package set to inches will be 25.4 times out.

If you need something this conversion cannot give you

This pair loses very little. 3MF carries what OBJ carries, so the main reason to choose a different target is what the receiving software accepts.

Going the other way

Convert 3MF back to OBJ. The reverse conversion also works with mesh geometry. It does not reconstruct exact CAD surfaces. Material data and part structure lost in either direction cannot be restored by converting back. Keep the original file for later edits.

How we know this conversion works

This pair was checked against 3 files from the test corpus on 2026-09-04. Each run parses its own output back in and compares the bounding box, the triangle count and, for closed solids, the volume against the input.

A pair that fails those checks doesn't get a page. That's why this site lists 120 conversions and not the several hundred a format-times-format grid would suggest.