Guide
How GLB and USDZ differ
Two file formats that hold 3D. A web browser reads GLB, and the AR viewer on iPhone and iPad reads USDZ.
In short
The same model, exported twice
GLB is one flavour of glTF 2.0. glTF is an open format from the Khronos graphics standards body, and it holds geometry, materials, textures and animation together. A gltf file keeps the description and the textures apart; a glb file holds all of it in one binary.
USDZ wraps Pixar's USD in an uncompressed package. The AR viewer on iOS and iPadOS reads this format. Put a USDZ link on a web page and tapping it moves straight into the system AR view.
So the job rarely ends with picking one. GLB to turn the model inside the page, USDZ to stand it in a real room on an iPhone, which is why the same model is usually exported twice.
Side by side
What actually differs
From who made them to how animation plays, limited to the differences that show up in real work.
| Item | GLB | USDZ |
|---|---|---|
| Made by | GLBKhronos (glTF 2.0) | USDZPixar (USD) |
| Packed as | GLBOne binary file | USDZAn uncompressed package |
| Read by | GLBWeb browsers, 3D editing tools | USDZThe AR viewer on iOS and iPadOS |
| Textures | GLBPNG, JPEG, KTX2 | USDZPNG, JPEG |
| Geometry compression | GLBDraco extension | USDZNone |
| Animation | GLBSeveral, played by choice | USDZOne at a time |
In practice
What catches you after the export
Matching the format does not make the two views match. Check the following.
- File size is the wait. Cut geometry with Draco and textures with KTX2. USDZ is not compressed, so lower the texture resolution before exporting.
- Colours often look different. Both formats use physically based materials, but they are not processed the same way, so open both views side by side after exporting.
- Conversion does not finish by itself. Tools do convert, but materials and animation do not always survive the trip, so check with your own eyes.
Common questions
Read next
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Augmented reality opened in a browser with no install. The kinds, and what happens after the link opens.
AR support by browser
Which way opens in which browser. Checked September 2026.
What RAG is
How a model is made to answer from your own material, and where it falls down.
How 3D runs in a browser
WebGL and WebGPU, the order of work, and what makes it slow.
Upload one and look at it
Vi3w takes a 3D model and hands back a link that opens in a browser.