GLB vs OBJ — What's the Difference?
OBJ has been around since the 1980s and is still used daily by millions of 3D artists. GLB was designed in 2017 with modern real-time rendering in mind. Understanding why both still exist — and when each is appropriate — is fundamental to managing a modern 3D asset pipeline.
What Is OBJ?
OBJ (Wavefront Object) was created by Wavefront Technologies for their Advanced Visualizer software in the 1980s. It is a plain-text format describing 3D geometry using a simple list of vertices, texture coordinates, normals, and face definitions.
A minimal OBJ file looks like this:
# A simple triangle v 0.0 0.0 0.0 v 1.0 0.0 0.0 v 0.0 1.0 0.0 vt 0.0 0.0 vt 1.0 0.0 vt 0.0 1.0 vn 0.0 0.0 1.0 f 1/1/1 2/2/1 3/3/1
Like ASCII STL, OBJ is human-readable, which makes it useful for debugging. Unlike STL, OBJ supports UV texture coordinates, multiple objects, and named groups.
The OBJ + MTL System
OBJ stores geometry. Materials are stored in a separate .mtl (Material Template Library) file. The OBJ file references the MTL file with a mtllib directive, and texture image files are stored as additional separate files.
A typical OBJ asset folder might contain:
model.obj— geometrymodel.mtl— material definitionstexture_diffuse.png— color texturetexture_normal.png— normal map
This multi-file structure is one of OBJ's biggest weaknesses — if any file gets separated from the others, materials break silently, and the geometry appears grey. This is exactly the problem GLB solves by embedding everything in one file.
If you email or share an OBJ file without its accompanying .mtl and texture files, the recipient sees only grey geometry. This happens constantly when people share models. GLB embeds all textures and materials in a single file, making this problem impossible.
Feature Comparison
| Feature | OBJ | GLB |
|---|---|---|
| Geometry | ✓ | ✓ |
| UV texture coordinates | ✓ | ✓ |
| Multiple objects/groups | ✓ | ✓ |
| Materials (PBR) | ✗ (MTL is Phong-based) | ✓ (native PBR) |
| Embedded textures | ✗ (separate files) | ✓ |
| Skeletal animation | ✗ | ✓ |
| Morph targets | ✗ | ✓ |
| Scene hierarchy | ✗ (flat) | ✓ |
| Human-readable | ✓ | ✗ |
| Web/AR native | ✗ | ✓ |
| Single self-contained file | ✗ | ✓ |
| Binary (compact) | ✗ | ✓ |
File Size
OBJ is plain text — verbose by design. Every vertex coordinate and face index is written as human-readable numbers. For the same model:
- A 100,000-polygon model in OBJ might be 8MB of text
- The same model in GLB binary is approximately 3–4MB
- With Draco compression, the GLB might be 400KB
GLB also avoids OBJ's duplication of shared vertices (OBJ stores vertices per-face, not per-mesh), further reducing size for models with smooth surfaces.
Tool Support
OBJ is supported by virtually every 3D tool ever made — Blender, Maya, 3ds Max, ZBrush, Cinema 4D, Fusion 360, Tinkercad, SketchUp, and hundreds of others. It has been the universal interchange format for 30+ years and will remain widely supported indefinitely.
GLB is supported by all modern 3D tools (Blender, Cinema 4D, Maya via plugin) and all web/AR/game runtimes. Its tool support is slightly less universal than OBJ's but covers all professional workflows.
When OBJ Still Wins
- Maximum tool compatibility — when you need to open a model in the widest possible range of software, OBJ is the safest bet
- Simple geometry without animation — for a static mesh with a texture, OBJ + MTL works fine and is universally understood
- Human inspection and editing — because OBJ is plain text, you can open it in a text editor and manually fix coordinate issues or rename objects
- STL-to-GLB intermediate step — converting from STL to OBJ+MTL to GLB preserves material colors that are lost in direct STL-to-GLB conversion
- Legacy software that cannot open GLB — some older 3D applications only support OBJ
When GLB Wins
- Web display — Three.js, Babylon.js, model-viewer: GLB is the only practical option
- AR experiences — Google SceneViewer, WebXR: GLB required
- Animated assets — OBJ has no animation support; GLB supports full skeletal animation and morph targets
- PBR materials — OBJ's MTL format is based on the Phong shading model from the 1970s; it cannot properly represent metallic, roughness, or emission. GLB's PBR materials are native
- Distribution — one self-contained file is dramatically easier to share than a folder of OBJ + MTL + textures
- Modern game engines (Godot, runtime Unity) — GLB loads directly without format conversion
Converting OBJ to GLB
The most reliable conversion paths:
- Blender — import OBJ (File → Import → Wavefront OBJ), then export as GLB (File → Export → glTF 2.0, select GLB). Materials will be converted from Phong to PBR automatically.
- obj2gltf (CLI) —
npm install -g obj2gltfthenobj2gltf -i model.obj -o model.glb. Fast and reliable for batch processing. - Sketchfab — upload the OBJ folder as a zip, view in Sketchfab, download as GLB.
OBJ materials use Phong properties (Kd for diffuse, Ks for specular, Ns for shininess). When converting to GLB's PBR system, these are approximated — diffuse maps become albedo, specular maps are approximated as metallic. The result is usually acceptable but not perfect. For best quality, re-apply PBR materials in Blender after conversion.
Frequently Asked Questions
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