STL vs GLB vs OBJ: Which 3D File Format Should You Use?
You finished a model and the download page offers several files. They are not interchangeable. Each format was designed for a different job, and picking the right one saves you from re-exporting or from a print that comes out gray.
At a glance
| STL | OBJ | GLB | |
|---|---|---|---|
| Stores | Geometry only (triangles) | Geometry, plus links to material and texture files | Geometry, materials and textures in one binary file |
| Color / texture | No | Yes, via separate .mtl and image files | Yes, embedded |
| Units | Not stored (unitless; slicers assume mm) | Not stored | Metres by convention |
| Best for | 3D printing | Editing in modelling software | Web, real-time engines, sharing |
| Number of files | 1 | Several | 1 |
STL: the 3D-printing standard
STL (originally from stereolithography) describes a surface as a list of triangles and nothing else. No color, no textures, no units. Every slicer, the program that turns a model into printer instructions, reads it, which is why it is the default for printing. Two consequences follow:
- Size must be set. Because an STL has no units, it is interpreted as millimetres by most slicers. In our tool you enter the largest dimension in millimetres (5 to 1000) and the STL is scaled to match, so a "100" gives a model whose longest side is 100 mm.
- The mesh should be watertight. A printer needs a closed solid. Gaps or holes in the surface can cause slicing errors. See preparing AI models for printing.
For multi-color printing, a plain STL is not enough; you would need a format that carries color such as 3MF or a set of separate parts.
OBJ: the old, universal exchange format
OBJ is a text-based format supported by practically every 3D program. It stores geometry in one file and refers to a material file (.mtl) and image files for the texture. That makes it easy to open in Blender and similar tools and edit by hand, but easy to break: if you move the .obj without its .mtl and texture image, the colors vanish. Keep them together in one folder. Our OBJ download comes with the texture for that reason.
GLB: the modern, single-file choice
GLB is the binary version of glTF, sometimes described as the "JPEG of 3D". Geometry, materials, textures and even animation can be packed into one self-contained file. It loads quickly, is supported by web viewers, Unity (with a package), Godot, Unreal (with plugins), Blender, and social platforms, and the viewer on this site uses it. If you are unsure, GLB is the safest choice for anything that will be viewed rather than printed.
Which one should you download?
- I want to 3D print it: STL, after setting the size in millimetres.
- I want it in a game or a website: GLB. See using AI models in game engines.
- I want to edit or texture it further in Blender: GLB imports cleanly and keeps materials; OBJ also works and is useful for older tools.
- I made a voxel model: the voxel editor also exports .vox (MagicaVoxel), GLB, OBJ and a PNG preview; see what is voxel art.
Other formats you may meet
FBX is common in game studios and animation pipelines but is proprietary; GLB is usually an adequate substitute. 3MF is a newer printing format that can carry color, units and multiple objects. USDZ is used for augmented reality on Apple devices. Any of them can be produced by importing the GLB or OBJ into a free tool like Blender and exporting again.
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