glTF vs GLB: What's the Difference and Which Should You Use?

glTF and GLB are the same 3D format, glTF 2.0, packaged in two different ways. A .gltf file is readable JSON that points to separate .bin geometry and texture files, while a .glb is one binary file with everything inside. Use GLB to deliver models to websites, AR and online stores, and use .gltf when you want to read, hand-edit or diff the scene.

Because the underlying data is identical, you can convert between the two without losing anything, and every serious glTF loader (three.js, Babylon.js, Blender, Godot and others) reads both. The choice is about packaging, not quality.

Same data, different packaging

A glTF asset always has two parts: a JSON scene description (nodes, meshes, materials, animations, cameras) and binary data (vertex positions, normals, UVs, indices, animation keyframes and texture images). The two file types only differ in where that binary data lives.

What's in a .gltf file

A .gltf is plain JSON. The binary data sits in separate files that the JSON references by relative path, so a typical export looks like chair.gltf, chair.bin and a handful of PNG or JPEG textures:

{
  "asset": { "version": "2.0" },
  "buffers": [
    { "uri": "chair.bin", "byteLength": 1048576 }
  ],
  "images": [
    { "uri": "chair_basecolor.jpg" },
    { "uri": "chair_normal.png" }
  ]
}

There's also an embedded variant where the .bin and images are stuffed into the JSON as base64 data URIs, giving you a single .gltf file. The glTF specification notes that base64 encoding increases the payload's byte length by 33%, and the data has to be decoded before use. Blender still offers this option, but hides it by default and calls it the least efficient form. If you want a single file, use GLB instead.

What's in a .glb file

A .glb (glTF Binary) is a small container: a 12-byte header starting with the magic bytes glTF, then a JSON chunk with the same scene description, then a binary chunk holding the buffer data. Textures are stored inside that binary chunk too, and the JSON points at them by byte range instead of by file name:

"buffers": [{ "byteLength": 1363968 }],
"images": [
  { "bufferView": 4, "mimeType": "image/jpeg" },
  { "bufferView": 5, "mimeType": "image/png" }
]

The spec does allow a GLB to reference external files (for example, to keep images separate), but in practice most GLB files are fully self-contained. For a closer look at the format, see what is a GLB file.

glTF vs GLB at a glance

When to use GLB

GLB is the right default whenever a model leaves your hands:

• Websites. One request, one file to cache and one path to reference in your code. See how to load a GLB in three.js.
• AR. Android's Scene Viewer and the <model-viewer> web component load glTF from a URL, and a GLB gives them one self-contained URL to load.
• E-commerce. Shopify accepts 3D product models as GLB or USDZ, not .gltf. More in 3D models on Shopify.
• Sharing and uploading. Sending a client or a marketplace a single file removes the classic "the textures are missing" problem.

When to use .gltf

.gltf with separate files is better while you're still working on an asset:

• Debugging. Open the JSON to see which extensions a model uses, what a material's factors are, or why a texture isn't showing up.
• Hand edits. Fix a texture path, rename a node or tweak a color without re-exporting from your 3D app.
• Version control. Git can show what changed in the JSON between two exports; the geometry and textures stay as separate files you can replace one at a time.
• Swapping or sharing textures. Replace an image file without touching the geometry, or let several models reference the same texture so browsers download it once.
• Lazy loading. Tools like gltf-transform can split the binary data into several .bin files so an app fetches only what it needs. Its partition command works on .gltf, not .glb.

To check what's inside a file in either format, run it through our free glTF validator. It shows errors, warnings, triangle counts, draw calls and the extensions in use.

How to convert glTF to GLB

The quickest way is our free glTF to GLB converter. Select the .gltf together with its .bin and texture files, and download a single GLB. It runs entirely in your browser, so nothing is uploaded and you don't need an account.

If you'd rather script it, the open-source gltf-transform CLI does the same:

npx @gltf-transform/cli copy model.gltf model.glb

In Blender, import the file with File > Import > glTF 2.0, then export with File > Export > glTF 2.0 and set the format to glTF Binary (.glb).

How to convert GLB to glTF

The same gltf-transform command works in reverse. The output format follows the file extension:

npx @gltf-transform/cli copy model.glb model.gltf

This writes model.gltf plus a .bin and the texture images next to it. In Blender, import the GLB and export with the glTF Separate (.gltf + .bin + textures) format.

Does the format change file size or compression?

Not really. A GLB and a separate-files .gltf of the same model add up to roughly the same number of bytes; GLB just puts them in one file. Converting glTF to GLB won't make a heavy model light. Only the embedded, base64 .gltf is meaningfully bigger.

Real size savings come from what's inside: Draco geometry compression, smaller textures in WebP or AVIF, and removing duplicate or unused data. All of these work the same on both formats, because they change the glTF data, not the packaging. The full list is in how to reduce GLB file size.

When you're ready to ship, our glTF and GLB compressor applies Draco, texture resizing and WebP/AVIF conversion in one pass and accepts either format. Typical results are 60–90% smaller, and the first compression is free with an account.

FAQ

Is GLB better than glTF?

For delivery, usually yes: one file, one request and no missing textures. For editing and debugging, .gltf is more convenient because you can read and change the JSON directly. Neither is higher quality, since both hold the same glTF 2.0 data.

Is GLB smaller than glTF?

Only compared with an embedded .gltf, where base64 adds about 33% to the binary data. Compared with a .gltf plus separate .bin and texture files, the total size is about the same.

Can I open a GLB file in a text editor?

You'll see the JSON near the start of the file, but the rest is binary, and editing it by hand breaks the chunk lengths. Convert it to .gltf, edit, and convert back.

Does three.js load both glTF and GLB?

Yes. three.js's GLTFLoader loads .gltf and .glb files; for a .gltf it fetches the referenced .bin and textures relative to the JSON's URL.

Should I upload glTF or GLB to Shopify?

GLB. Shopify's 3D model media accepts GLB and USDZ files, and it creates the other format automatically so the model works on both Android and iOS.