claygroundExport GLB when you want to keep the sculpt’s colour and layers, for Blender, a game engine, the web or sharing. Export STL when the only goal is a 3D print. Export OBJ when a program can’t read GLB and you only need the shape. GLB is one self-contained file; STL and OBJ keep geometry and drop most everything else.
What each one keeps
| Topic | GLB | OBJ | STL |
|---|---|---|---|
| Shape | Yes | Yes | Yes |
| Colour | Yes, including vertex colours | Only through a separate material file | No |
| Separate layers or parts | Yes | Yes, as groups | No, one lump |
| Animation | Yes | No | No |
| Single self-contained file | Yes | No, usually plus .mtl and images | Yes |
| Main use | Web, games, Blender, sharing | Older tools, simple shape swap | 3D printing |
GLB: the one to keep
GLB is the binary form of glTF, a format built for delivering 3D to the web and engines. Everything lives in one file: geometry, materials, vertex colours, and animation. That is why it is the safe master copy. If you only keep one file of a sculpt, keep the GLB.
It is also what opens in the most places without fuss: Blender, Unity, Godot, Three.js, and most online viewers. You can check any GLB, and see its triangle count, in the free GLB viewer.
OBJ: plain shape, widely readable
OBJ is an old, simple text format. It stores the shape and, through a companion .mtl file, basic materials. Paint stored as vertex colours is generally not carried over, so a painted clay sculpt can come out as plain grey.
Reach for OBJ when something you use cannot open GLB. Otherwise there is little reason to prefer it.
STL: for printers
STL describes a surface as a pile of triangles and nothing else: no colour, no layers, no units. That bluntness is why slicers all accept it. It is the right file for printing and the wrong file for almost anything else.
Two things catch people out. STL has no units, and most slicers assume millimetres, while a GLB is in metres, so a model exported unscaled can arrive as a speck. And many slicers expect Z as up, while glTF uses Y. The GLB to STL converter lets you set both. For the printing side, see print your fella.
A quick way to choose
- Going to Blender or a game? GLB. See exporting a GLB to Blender.
- Going to a 3D printer? STL. In the browser studio, Print (STL) gives a ready 60 mm file.
- A tool that only reads OBJ? OBJ, and expect to repaint.
- Not sure? Export the GLB too. You can always make an STL from it later, but you cannot get the colour back out of an STL.
Questions people ask
Is GLB better than OBJ?
For colour, layers and animation, yes: GLB keeps them and OBJ mostly does not. OBJ is only better when software can’t open GLB.
Why did my STL print come out tiny?
STL has no units. A GLB is in metres, and slicers read the numbers as millimetres, so a 1 metre model reads as 1 mm. Scale by 1000 when you convert.
Can I turn an STL back into a coloured model?
No. STL never stored the colour. Keep the GLB as your master and make STL copies from it.
Can I convert GLB to STL for free?
Yes. The GLB viewer and converter does it in your browser, with nothing uploaded.
Sources
Checked 16 October 2026.