FORMAT COMPARISON
GLB vs GLTF — What Is the Difference?
Same format, different packaging. One binary file versus JSON plus external assets — here is when each makes sense.
One format, two containers
glTF 2.0 is a single specification maintained by the Khronos Group. It defines how meshes, materials, textures, animations, and scene hierarchy are stored. The spec allows two packaging options:
- .gltf — a JSON file that describes the scene, plus separate
.binfiles for geometry buffers and external image files for textures. Human-readable; easy to edit with a text editor or a script. - .glb — a single binary file with a 12-byte header, a JSON chunk, and a BIN chunk. Everything is packed together: one file, one HTTP request, no external dependencies.
The scene data is identical in both forms. A .glb can be unpacked into a .gltf + .bin + images and repacked without any loss. The choice is about workflow convenience, not capability.
Side-by-side comparison
| .glb (GL Binary) | .gltf (GL Transmission Format) | |
|---|---|---|
| File count | 1 file | 2+ files (JSON + .bin + images) |
| Format | Binary container | JSON text + external binaries |
| Human-readable | No (binary) | Yes (JSON, editable in any text editor) |
| Texture storage | Embedded as binary — compact | External files, or Base64 in JSON (+33% size) |
| Typical file size | Smaller (no Base64 overhead) | Similar payload, but more HTTP requests |
| Web loading speed | Faster (single request) | Slower (multiple requests for buffers/images) |
| Editability | Requires a tool to unpack | Edit JSON directly, swap textures by path |
| Tool support | three.js, Babylon, model-viewer, Unity, Unreal, Godot, Blender | Same tools — identical format |
| Best for | Distribution, web, AR, sharing | Development, hand-editing, shared texture libraries |
When to use GLB
- Web embedding — <model-viewer>, three.js, Babylon.js all prefer a single .glb. One file, one fetch.
- AR — Android SceneViewer loads GLB directly. Apple Quick Look wants USDZ, but GLB is the starting point for conversion.
- Sharing a model — one file instead of a folder of JSON, bins, and images. Nothing gets lost in transit.
- AI model generators — Meshy, Tripo, Rodin, and Luma export GLB by default.
When to use GLTF
- Hand-editing the scene — the JSON is human-readable. Change a material property, swap a texture path, or strip an animation without opening a 3D editor.
- Shared texture libraries — multiple .gltf files can reference the same external image, saving storage when a set of models share a material atlas.
- Version control — diffing JSON is meaningful; diffing a binary blob is not. Teams that track assets in git sometimes prefer .gltf for that reason.
- Build pipelines — tools like glTF-Transform and gltf-pipeline can optimize a .gltf (Draco compression, texture resizing) and then pack the result as .glb for production.
Neither is printable
glTF (whether .glb or .gltf) is a web/AR format. Slicers want STL or 3MF. To print a glTF model, convert to STL — materials, textures, and animation are dropped; geometry is kept. The GLB to STL converter on this site does that extraction in the browser. The reverse — taking a print file to the web — is the STL to GLB converter.
For more on the format itself, see What is a GLB file? which covers the glTF 2.0 specification, PBR materials, and where GLB files come from.
FAQ
Is GLB the same as GLTF?+
Yes — same format, different packaging. A .gltf is JSON text plus separate .bin and image files. A .glb wraps all of that into one binary file. The scene data, materials, and geometry are identical; only the container differs.
Which is smaller, GLB or GLTF?+
GLB is usually smaller. Textures embedded in a .gltf are Base64-encoded, which inflates size by about 33%. A .glb embeds the same texture data as raw binary — no encoding overhead. If the .gltf uses external file references instead of Base64, the total payload is similar, but it takes multiple HTTP requests to load.
Can I convert between GLB and GLTF?+
Yes, losslessly. Tools like gltf-pipeline, glTF-Transform, and Blender can unpack a .glb into .gltf + .bin + images, or pack the other way. No geometry is lost because the underlying format is identical.
Which should I use for a website?+
GLB. One file, one HTTP request, no Base64 overhead. three.js, Babylon.js, and model-viewer all load GLB natively. Use .gltf only if you need to edit the JSON by hand or reference external textures that multiple models share.
Do game engines prefer GLB or GLTF?+
Unity and Unreal import both. Godot imports .gltf natively and .glb via its built-in importer. In practice, .glb is more common for distribution because it is a single file; .gltf is sometimes used during development when the JSON needs to be inspected.