Question 1

What happens to the .mtl file and textures?

Accepted Answer

They are ignored. The converter reads only the .obj geometry, and STL has no place for colour or texture anyway. Keep the OBJ, MTL and images together if you need them later, for example to render the model in Blender.

Question 2

Why is my model tiny (or huge) after converting OBJ to STL?

Accepted Answer

OBJ and STL store plain numbers without units, and slicers read STL as millimetres. If the OBJ was modelled in metres, choose Metres → millimetres or Fit longest side to 100 in the Scale menu. The size panel shows the result before you download.

Question 3

Why is my model lying on its back in the slicer?

Accepted Answer

Most OBJ exports are Y-up, while slicers expect Z-up. Leave “Stand upright for the new format” on and the converter turns the model as it writes the STL. Switch it off only if you have already rotated the model yourself.

Question 4

Can I convert several OBJ files to STL at once?

Accepted Answer

Yes. Drop up to 10 OBJ files, each up to 200 MB, and click Convert all. Batch OBJ to STL applies the same scale and orientation settings to every file, and each STL downloads with its original name.

Question 5

What is the difference between STL and OBJ?

Accepted Answer

Both describe a surface with polygons. OBJ can also hold UVs, normals and a link to materials, so it suits Blender and game engines. STL keeps only triangles, which is all a slicer needs. Going the other way? Use the STL to OBJ converter below.

Question 6

Is it safe to convert OBJ to STL here?

Accepted Answer

Yes. Your file is read and converted locally in the browser and never uploaded. There is no account, no queue and no copy on our servers, so it suits client work and designs under NDA.

Question 7

Does the OBJ to STL converter repair the mesh?

Accepted Answer

No. It changes the format, orientation and scale, but doesn't close holes or fix non-manifold edges. If the STL needs fixing, use the repair option in your slicer or a mesh tool such as Blender or MeshLab.

Question 8

Can I convert PLY to STL here too?

Accepted Answer

Yes. PLY to STL works just like OBJ to STL: drop a .ply from a 3D scanner, a photogrammetry app or MeshLab and download a binary STL. Vertex colours are dropped, and a point cloud without faces can't be converted, because STL needs triangles.

Question 9

Is this OBJ to STL converter free? Do I need to sign up?

Accepted Answer

It's free and needs no sign-up: open the page, drop your OBJ and download the STL, up to 200 MB per file and 10 files per batch. You only need an account to generate new 3D models from a photo or text.

Question 10

Can I convert OBJ to STL in Blender instead?

Accepted Answer

Yes, if Blender is installed: File → Import → Wavefront (.obj), then File → Export → STL. This converter is quicker when you only need the file: nothing to install, it runs in a browser tab, stands the model upright and rescales it before download.

OBJ to STL: what changes in the file	OBJ	STL
Mesh geometry	Yes	Yes
UV coordinates	Yes	No
Colours, textures	Via .mtl	No
Up axis	Usually Y	Z
Made for	3D apps	Printing

OBJ to STL Converter That Runs in Your Browser

What the converter gives you

How to convert OBJ to STL

Add the OBJ

Check size and orientation

Download the STL

OBJ to STL: what changes in the file

From mesh to printable part

Why use this OBJ to STL converter

Stands upright

Real-world size

Batch OBJ to STL

PLY to STL as well

Nothing uploaded

Preview first

OBJ to STL FAQ

More ways to work with your 3D files

STL to OBJ converter

3MF to STL converter

STL viewer

Image to STL

Want something new to print?