Wandy3D

Free converter

STL to OBJ converter

Turn an STL into an OBJ that 3D apps import at the right size and the right way up. It's made in your browser — free, with no account and no upload.

  • No sign-up
  • Runs in your browser · nothing uploaded
  • STL up to 50 MB

What changes

What changes when an STL becomes an OBJ

STL comes from printers and CAD, OBJ goes into 3D apps. Here's what the conversion does.

  • Millimetres become metres

    An OBJ carries no unit, and Blender and Unity read one unit as one metre. We write metres from the STL's millimetres (or the unit you pick), so the model keeps its real size.

  • Z-up becomes Y-up

    STL files come from slicers and CAD apps, which work with Z up. OBJ apps expect Y up, so we turn the model to stand upright.

  • Shared corners

    STL repeats each corner for every triangle. The OBJ lists every vertex once and builds the faces from them — a clean mesh to edit in a 3D app.

  • The shape alone

    An STL has no colours, UVs or normals, so you get one .obj with the shape and no MTL. Apps work out the shading themselves.

How it works

STL to OBJ in three steps

  1. 1

    Drop your STL

    Binary or ASCII, up to 50 MB and 2 million triangles.

  2. 2

    Check the unit

    STL is read as millimetres; change it to cm, m or inches if the size looks wrong.

  3. 3

    Convert to OBJ

    The .obj is written in your browser and downloads at once.

Your file stays on your device

  • Converted in your browser — the file never leaves your device, so we never see it.
  • No account and no daily limit.
  • GLB, STL, OBJ or 3MF, up to 50 MB and 2 million triangles.
  • Only formats made on our servers (OBJ from a GLB, USDZ, FBX) upload a file — privately, deleted after 29 days, never used to train AI.

Details in our Privacy Policy.

Questions

STL to OBJ: questions

More answers in Support

Yes. It runs entirely in your browser — no account, no daily limit, no upload.

Metres, with Y up — the way Blender and Unity read OBJ. A 100 mm STL becomes an OBJ 0.1 units tall. If an app shows it 1,000 times too small, it reads the numbers as millimetres: set its import unit to metres or scale by 1,000 there.

No — an STL holds only the shape, so there is nothing to carry over. Want a textured model? Make one from a photo with Wandy3D.

No. Every triangle is kept: identical corners are merged into one vertex and triangles that collapse to a line are dropped. Coordinates are written to a tenth of a micrometre.

There are no materials to describe. Converting a GLB with textures? That OBJ comes as a ZIP with the MTL and the texture images — see GLB to OBJ.

No. Your browser reads the STL and writes the OBJ; nothing is sent to us.

Other conversions

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Or check a file for 3D printing, or see how a photo becomes an STL.

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