STL vs OBJ vs GLB: what is the difference?

The extensions can appear interchangeable because all three open in 3D software. They carry different data, however, so the consequences of choosing the wrong one often emerge only after transfer or import.

STL

STL describes a surface with triangles. It normally contains no materials, textures, scene hierarchy or reliable unit information. Its main advantage is broad slicer compatibility.

Practical next step: Inspect a model in the STL Viewer

An STL may contain several shells, but it does not explain what each shell represents.

OBJ

OBJ carries a mesh, normals and UV coordinates. Materials are usually described in a separate MTL file, with image files stored alongside it. Send the OBJ alone and its appearance may be lost.

OBJ works well in editors and for simple textured models, but the associated files must be managed carefully.

GLB

GLB is the binary form of glTF. It can package a scene, materials, textures and sometimes animation data in one file, making it practical for the web, previews and exchange.

To print a GLB, import it, select the required objects, combine the geometry and export a print-oriented format.

What happens to textures?

Surface colour does not become physical relief. Textures normally disappear when GLB or OBJ is exported as STL. If an ornament needs to print, it must exist as geometry or as separately printable colour parts.

Which format should you choose?

• STL: quick exchange with almost any slicer;
• OBJ: mesh editing with external material files;
• GLB: one file that retains the visual appearance;
• 3MF: a modern 3D-printing project;
• STEP: precise CAD geometry.

Keep the source GLB or OBJ and make a separate STL for printing.

Example

A figurine from AIPRINTGEN is shown to the client as a coloured GLB. It is then imported into Blender, where the textures are extracted as painting references and a watertight STL is exported. The slicer receives geometry, while the artist uses the images as guidance.

Mistakes and limitations

An OBJ without its MTL and textures appears grey. An STL may open at the wrong scale. A GLB can contain lights, cameras and several objects. Simply renaming the extension does not convert the underlying data.

Practical next step: Open the 3D file converter

Frequently asked questions

Conclusion

STL, OBJ and GLB are not rivals; they serve different stages. Choose the format that preserves the data you need and create a separate export for printing.