The two formats answer different questions. FBX is the working interchange of animation and engine pipelines; GLB is the delivery format of the web era - one file, textures included, readable by every browser and viewer. Moving between them in Blender takes minutes. The five traps below are where the minutes turn into hours.
The conversion, step by step
01 - Import the FBX. In the import dialog, watch the scale setting. FBX files are frequently authored in centimetres, and the importer will happily bring in a model that is 100 times too big or too small. Import, measure a known dimension, and only then continue.
02 - Check the textures. FBX references images as file paths. If the paths broke on the way to you, the model arrives grey or pink. Re-link the images in the shader editor before anything else.
03 - Sanity-check the materials. Most FBX material setups rebuild cleanly in Blender. Complex ones arrive as a tangle of nodes; glance at the Principled BSDF and make sure base colour, roughness and normal inputs are actually connected.
04 - Fix scale and orientation. GLB is Y-up by convention and Blender exports the conversion for you - but only if the scene itself is clean. Apply rotation and scale on the objects you are exporting, and put the origin somewhere sensible.
05 - Export GLB. File, Export, glTF 2.0, choose the .glb extension. Include selected objects, export materials, and decide about image format - leaving textures as-is is fine unless the file is going to the web, where re-encoding to JPEG or WebP cuts the size dramatically.
06 - Verify in a viewer. Drop the GLB into any viewer and check three things: textures present, animation present, no obvious normal errors. This is the step everyone skips and everyone regrets.
The five traps
| Symptom | Cause and fix |
|---|---|
| Pink or missing textures | Broken image paths or unpacked textures. Re-link, then pack resources before exporting. |
| Enormous file size | Uncompressed textures riding along. Re-encode images to JPEG or WebP in the export options. |
| Model 100x too big or small | The centimetre-versus-metre classic. Fix the scale at import, not after a dozen edits. |
| Flat, wrong-looking shading | Normals need recalculating, or a normal map lost its connection in the material rebuild. |
| Animation missing | The export was run in a mode that skips actions, or the range was clipped to a single frame. Re-export with animation enabled and verify in the viewer. |
When the source is generated
AI-generated assets usually arrive as GLB or OBJ, which means this conversion often runs backwards - GLB to FBX - on the way to Unity or Unreal. Both directions are the same skill set: check scale, re-link textures, rebuild the material, verify. If your pipeline runs the other way, the mirrored guide covers GLB to FBX with the same checklist.
Where it stops
Blender is not a batch file juggler out of the box, and it is not interested in rescuing a file that was exported badly upstream. If a conversion keeps misbehaving, the fault is usually in the FBX itself - embedded scale, non-standard rigs, baked materials - and the fastest fix is to go back to the source DCC and export again. Blender will happily convert a clean file; it will not make a broken one clean.